Taximeters

Metrological and technical requirements, 

test procedures and test report format

Taximètres

Exigences métrologiques et techniques, procédures d’essais

et format du rapport d’essais 

OIML R 21 Edition 2007 (E)

OIML R 21

Edition 2007 (E)

ORGANISATION INTERNATIONALE

DE MÉTROLOGIE LÉGALE

INTERNATIONAL ORGANIZATION

OF LEGAL METROLOGY

INTERNATIONAL

RECOMMENDATION

OIML R 21: 2007 (E) 

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Contents 

Foreword .................................................................................................................................................................5

1 SCOPE ...........................................................................................................................................................6

1.1 Application .............................................................................................................................................6

1.2 Principle of operation .............................................................................................................................6

2 TERMINOLOGY..........................................................................................................................................6

2.1 General ...................................................................................................................................................6

2.2 Construction ...........................................................................................................................................7

2.3 Metrological characteristics....................................................................................................................9

2.4 Indications and errors ...........................................................................................................................12

2.5 Test conditions......................................................................................................................................13

3 METROLOGICAL REQUIREMENTS ...................................................................................................15

3.1 Main function of the taximeter .............................................................................................................15

3.2 Maximum permissible errors (MPE) ....................................................................................................15

3.3 Taximeter accuracy conformance over time.........................................................................................16

3.4 Units of measurement...........................................................................................................................16

3.5 Variations due to influence quantities ..................................................................................................16

3.6 Taximeter constant, k............................................................................................................................16

3.7 Real-time clock.....................................................................................................................................17

4 TECHNICAL REQUIREMENTS.............................................................................................................17

4.1 Suitability for use .................................................................................................................................17

4.2 Security of operation ............................................................................................................................17

4.3 Fare calculation ....................................................................................................................................18

4.4 Tariff programming ..............................................................................................................................19

4.5 Operating position device.....................................................................................................................19

4.6 Additional requirements for the operating position device...................................................................20

4.7 Totalizers ..............................................................................................................................................21

4.8 Automatic change of tariffs ..................................................................................................................21

4.9 Indicating and printing..........................................................................................................................21

4.10 Data storage..........................................................................................................................................22

4.11 Software................................................................................................................................................23

4.12 Descriptive markings............................................................................................................................23

4.13 Verification marks ................................................................................................................................24

4.14 Installation and test conditions .............................................................................................................25

5 ELECTRONIC REQUIREMENTS ..........................................................................................................25

5.1 General requirements............................................................................................................................25

5.2 Functional requirements .......................................................................................................................26

5.3 Examination and tests...........................................................................................................................28

6 METROLOGICAL CONTROLS..............................................................................................................29

6.1 General .................................................................................................................................................29

6.2 Type approval.......................................................................................................................................29

6.3 Initial verification .................................................................................................................................31

6.4 Subsequent metrological control ..........................................................................................................31

7 TEST METHOD .........................................................................................................................................32

7.1 General .................................................................................................................................................32

7.2 Functional tests according to the featured calculation method (A.4)....................................................32

7.3 Visual examination (A.4.2)...................................................................................................................33

7.4 Test report format .................................................................................................................................33

7.5 Program of functional tests...................................................................................................................34
OIML R 21: 2007 (E) 

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Annex A (Mandatory) Test procedures for taximeters.....................................................................................35

A.1 Examination for type approval (6.2) .............................................................................................................35

A.2 Examination for initial verification (6.3).......................................................................................................35

A.3 General test requirements..............................................................................................................................35

A.4 Functional tests (7.2).....................................................................................................................................35

A.5 Performance tests ..........................................................................................................................................38

Annex B (Informative) General information on the conditions for the compatibility 

between a taximeter and a distance measurement transducer.........................................................................57

Annex C (Mandatory) Test report format.........................................................................................................59

Bibliography .......................................................................................................................................................109
OIML R 21: 2007 (E) 

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Foreword 

The International Organization of Legal Metrology (OIML) is a worldwide, intergovernmental organization 

whose primary aim is to harmonize the regulations and metrological controls applied by the national 

metrological services, or related organizations, of its Member States. The main categories of OIML publications 

are: 

 International Recommendations (OIML R), which are model regulations that establish the 

metrological characteristics required of certain measuring instruments and which specify methods and 

equipment for checking their conformity. OIML Member States shall implement these 

Recommendations to the greatest possible extent; 

 International Documents (OIML D), which are informative in nature and which are intended to 

harmonize and improve work in the field of legal metrology; 

 International Guides (OIML G), which are also informative in nature and which are intended to give 

guidelines for the application of certain requirements to legal metrology; and 

 International Basic Publications (OIML B), which define the operating rules of the various OIML 

structures and systems. 

OIML Draft Recommendations, Documents and Guides are developed by Technical Committees or 

Subcommittees which comprise representatives from the Member States. Certain international and regional 

institutions also participate on a consultation basis. Cooperative agreements have been established between the 

OIML and certain institutions, such as ISO and the IEC, with the objective of avoiding contradictory 

requirements. Consequently, manufacturers and users of measuring instruments, test laboratories, etc. may 

simultaneously apply OIML publications and those of other institutions. 

International Recommendations, Documents, Guides and Basic Publications are published in English (E) and 

translated into French (F) and are subject to periodic revision. 

Additionally, the OIML publishes or participates in the publication of Vocabularies (OIML V) and periodically 

commissions legal metrology experts to write Expert Reports (OIML E). Expert Reports are intended to 

provide information and advice, and are written solely from the viewpoint of their author, without the 

involvement of a Technical Committee or Subcommittee, nor that of the CIML. Thus, they do not necessarily 

represent the views of the OIML. 

This publication - reference OIML R 21, edition 2007 (E) - was developed by the OIML Technical 

Subcommittee TC 7/SC 4 Measuring instruments for road traffic. It was approved for final publication by the 

International Committee of Legal Metrology in 2007 and will be submitted to the International Conference of 

Legal Metrology in 2008 for formal sanction. This Edition supersedes the previous edition of OIML R 21 

(Edition 1973). 

OIML Publications may be downloaded from the OIML web site in the form of PDF files. Additional 

information on OIML Publications may be obtained from the Organization’s headquarters: 

Bureau International de Métrologie Légale 

11, rue Turgot - 75009 Paris - France 

Telephone: 33 (0)1 48 78 12 82 

Fax: 33 (0)1 42 82 17 27 

E-mail: biml@oiml.org 

Internet: www.oiml.org 
OIML R 21: 2007 (E) 

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Taximeters 

1 SCOPE 

This International Recommendation specifies the metrological and technical requirements and test 

procedures for taximeters that are subject to national metrological control. 

It is intended to provide standardized requirements and testing procedures to evaluate the metrological 

and technical characteristics in a uniform and traceable way. 

1.1 Application 

This Recommendation applies to taximeters that calculate fares charged for journeys according to 

defined tariffs. 

This Recommendation does not apply to mechanical taximeters. 

1.2 Principle of operation 

A distance measurement transducer (2.2.4) installed in the taxi provides the taximeter with distance 

information. The taximeter receives the output signal(s) from the distance measurement transducer and 

the time measuring signal, analyses and converts the signal(s) into the distance measurement signal. 

Together with the time measuring signal the taximeter calculates the fare, totalizes, displays and 

possibly records the results due for a taxi journey based on specified tariffs and/or the length and/or 

the duration of the journey. 

2 TERMINOLOGY 

The terminology used in this Recommendation conforms to the International Vocabulary of Basic and 

General Terms in Metrology [1], the International Vocabulary of Terms in Legal Metrology [2], the 

OIML Certificate System for Measuring Instruments [3], and the OIML International Document 

General requirements for Electronic Measuring Instruments [4]. In addition, for the purposes of this 

Recommendation, the following definitions apply. 

2.1 General 

2.1.1 Taximeter 

Instrument intended to measure duration and distance on the basis of a signal delivered by a distance 

measurement transducer, and to calculate and indicate the fare to be paid on the basis of the measured 

distance and/or duration. 

2.1.2 Taxi 

Vehicle, typically a car controlled by a driver, that takes passengers on a journey in exchange for a 

fare. 

2.1.3 Metrological authority 

Legal entity (i.e. the verification, issuing authority, accredited body, etc), designated or formally 

accepted by the government to be responsible for ascertaining that the instrument satisfies all or some 

specific requirements of this Recommendation. 
OIML R 21: 2007 (E) 

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2.1.4 Metrologically relevant 

Any device, instrument, function or software (of a taximeter) that influences the measurement result or 

any other primary indication is considered as metrologically relevant. 

2.1.5 Legally relevant 

Part of a measuring instrument, device or software subject to legal control. 

2.2 Construction 

2.2.1 Device 

In this Recommendation the term “device” is used for any means by which a specific function is 

performed irrespective of the physical realization e.g. by a mechanism or a key initiating an operation; 

the device may be a small part or a major portion of an instrument. 

2.2.2 Real-time clock 

Device incorporated into the taximeter that tracks the current time and date. 

2.2.3 Event-counter 

Non-resettable counter device that increments each time device-specific parameters (2.2.8.3) are 

changed. The reference number of the counter at the time of initial or subsequent verification is fixed 

and secured by appropriate hardware or software means. 

2.2.4 Distance measurement transducer 

Device installed in a taxi that converts the distance to be measured into pulses or digital data which are 

passed to the taximeter. 

2.2.5 Interface 

Electronic, optical, radio or other hardware and software connection means that enables information to 

be automatically passed between several measuring instruments or devices or between several 

different software modules. 

2.2.6 User interface 

Interface that enables information to be interchanged between a human user and the measuring 

instrument or its hardware or software components, e.g. switches, keyboard, mouse, display, monitor, 

printer, touch-screen, or a window on a screen including the software that generates it. 

2.2.7 Protective interface 

Interface which only allows the introduction of data into the data processing device of the taximeter, 

which cannot: 

 display data that are not clearly defined and which could be taken as being a measurement 

result; 

 falsify displayed, processed or stored measurement results or primary indications; 

 adjust the instrument or change any adjustment factor. 
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2.2.8 Software 

2.2.8.1 Legally relevant software 

Programs, data, type-specific and device-specific parameters that belong to the taximeter, and define 

or fulfill functions that are subject to legal control. 

2.2.8.2 Type-specific parameter 

Legally relevant parameter with a value that depends on the type of taximeter only. They are fixed at 

type approval of the taximeter. Examples of type-specific parameters include software identification 

and parameters used for fare calculation and rounding. 

2.2.8.3 Device-specific parameter 

Legally relevant parameter that depends on the individual taximeter. Such parameters comprise 

adjustment and configuration parameters. They are adjustable or selectable only in a service mode of 

the taximeter and may be classified as those that should be secured and those that may be accessed 

(settable parameters). 

2.2.8.4 Software identification 

Sequence of readable characters of software, and that is inextricably linked to the software (e.g. 

version number, checksum). 

2.2.8.5 Software protection 

Securing of measuring instrument software by a hardware or software implemented seal which has to 

be removed, damaged or broken to obtain access to change software. 

2.2.8.6 Software separation 

Software in measuring devices can be divided into a legally relevant part and a legally irrelevant part. 

These parts communicate via an interface. 

2.2.8.7 Data storage device 

Storage on the instrument or external storage device used for keeping measurement data ready after 

completion of the measurement for subsequent legally relevant purposes. 

2.2.9 Taxi identification number 

Numbers and/or letters identifying the taxi or the national registration number specified for the taxi. 

2.2.10 Printing device (printer) 

Device used to produce hardcopies (printouts) of the measurement results. 

2.2.11 Operating position device 

Device to switch the taximeter into specific operating positions (see 2.3.3). 

The operating position device may, for example, consist of specific keys and switches for specific 

functions. 
OIML R 21: 2007 (E) 

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2.3 Metrological characteristics 

2.3.1 Measurement data 

2.3.1.1 Fare 

Monetary amount calculated, indicated and displayed as a fare by the taximeter, due for a taxi journey 

based on a fixed initial fee (excluding any supplementary charges) and/or the length and/or the 

duration of the journey. 

2.3.1.1.1 Supplementary charges 

Additional monetary amount for an extra service, entered on manual command, suitably identified, 

indicated and displayed separately from the fare in “Hired” (occupied) and in “Stopped” (To Pay) 

operating positions, with the possibility to temporarily add to the fare and display the total value of the 

fare including the supplementary charge at the end of the journey. 

2.3.1.1.2 Initial hire fee (or initial charge) 

First increment of fare indication upon activation of the taximeter. 

2.3.1.1.3 Fare increment step 

Smallest amount of money by which the fare may be incremented in equal steps in “Hired” (Occupied) 

operating position in accordance with the national regulations. 

2.3.1.2 Cross-over speed 

Speed of the taxi (km/h) at which the time-counting and distance-counting methods operate the 

taximeter at the same rate. The speed value is determined by division of the time tariff value by the 

applicable distance tariff value. 

The cross-over speed is calculated as: 

Distance tariff [amount/km]

[amount/h] tariffTime

For example: 

Time tariff: $ 60.00/h 

Distance tariff: $ 3.00/km 

Cross-over speed [km/h]: 3.00/km $

60.00/h $ = 20 km/h
OIML R 21: 2007 (E) 

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2.3.1.3 Fare calculation method 

2.3.1.3.1 Normal calculation method, S (single application of tariff) 

Fare calculation based on application of the time tariff below the cross-over speed and application of 

the distance tariff above the cross-over speed. 

2.3.1.3.2 Normal calculation method, D (double application of tariff) 

Fare calculation based on the combined application of time tariff and distance tariff over the whole 

journey. 

2.3.1.4 Taximeter constant, k

Constant expressed in pulses per kilometre which represents the number of pulses the taximeter must 

receive in order to correctly indicate a distance traveled of one kilometre. 

2.3.1.5 Initial distance 

Distance which can be traveled according to the tariff for the initial hire fee, considering distancecounting only. 

2.3.1.6 Initial time 

Period during which the taxi can be used for the initial hire fee, considering time-counting only. 

2.3.1.7 Time-counting 

Time-counting is the calculation method in which the fare increases in proportion to the duration of 

the journey. 

2.3.1.8 Distance-counting 

Distance-counting is the calculation method in which the fare increases in proportion to the distance 

traveled. 

2.3.1.9 Time-distance counting 

Time-distance counting is the calculation method in which two components of the fare increase 

concurrently, one in proportion to the duration of the journey and the other in proportion to the 

distance traveled. 

2.3.1.10 Distance measuring signal 

Signal supplied by the distance measurement transducer to the taximeter, in proportion to the distance 

traveled. 

2.3.1.11 Time measuring signal 

Signal supplied by a clock incorporated in the taximeter, in proportion to the duration of the journey. 
OIML R 21: 2007 (E) 

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2.3.1.12 Reference number of pulses 

Theoretical number of pulses from a distance and/or time measuring signal, which can be calculated 

using the tariff data and the taximeter constant, k, which should lead to a certain change in the fare 

indication. 

2.3.1.13 Tariff 

Set of tariff values (including initial time / initial distance) that represents a schedule of charges or 

rates which will be operative in the taximeter in a specified tariff position. 

2.3.1.14 Tariff values 

Values from which the taximeter calculates the fare. 

2.3.1.15 Distance tariff value 

Tariff value expressed as an amount of money for a given distance. 

2.3.1.16 Time tariff value 

Tariff value expressed as an amount of money for a given period of time. 

2.3.1.17 Tariff position 

Position to which the taximeter can be adjusted in the “Hired” (Occupied) operating position. 

2.3.2 Tariff regulation 

Regulation, establishing which tariffs and supplements are to be applied under specified conditions. 

2.3.3 Operating position 

Specific operating position in which a taximeter fulfils different parts of its functioning. 

2.3.3.1 “For Hire” (Free) operating position 

Operating position in which the taximeter is not calculating a fare and no paying customer is making a 

taxi journey. 

2.3.3.2 “Hired” (Occupied) operating position 

Operating position in which the taximeter is indicating and calculating a fare which is based on a 

possible initial hire fee and a tariff for the time of the journey and/or distance traveled. 

2.3.3.3 “Stopped” (To Pay) operating position 

Operating position in which the taximeter is indicating a fare at the end of a fare-paying journey. 

2.3.3.4 “Measure” operating position 

Operating position in which the total distance and duration of the journey are measured and indicated. 
OIML R 21: 2007 (E) 

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2.3.4 Repeatability [VIM:1993, 3.6 [1]] 

Ability of a taximeter to provide results that agree one with the other under the same operating 

conditions of measurement. 

2.3.5 Durability 

Ability of a taximeter to maintain its performance characteristics over a period of use. 

2.3.6 Audit trail 

Continuous data file containing an information record or event-counter (2.2.3) of the changes to the 

values of device-specific parameters, of software updates or other activities or events that are legally 

relevant and which may influence the metrological characteristics. Every log entry has a unique time 

and date stamp. 

2.3.7 Operational mode 

Mode in which the taximeter is fully operational and implements all functions, including security 

functions. 

2.3.8 Service mode 

Mode for updating or confirming the taximeter parameters to be held in the memory storage. 

2.4 Indications and errors 

2.4.1 Indications of an instrument 

Value of a quantity provided by a measuring instrument. 

Note: “Indication”, “indicate” or “indicating” includes both displaying and/or printing. 

2.4.2 Digital indication [VIM:1993, 4.11 [1]] 

Indication in which the output or display of the measurement results is digitized. 

Note: The term “digitized” relates to the form of presentation of the output or display, not to the 

principle of operation of the instrument. 

2.4.3 Primary indications 

Indications, signals and symbols designed to or which may be used to display the fare, that are subject 

to requirements of this Recommendation. 

2.4.4 Totalization indication 

Indication mode to display the totalized values, clearly different from other values. 
OIML R 21: 2007 (E) 

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2.4.5 Errors 

2.4.5.1 Error (of indication) [VIM:1993, 5.20 [1]] 

Indication of an instrument minus a true value of the corresponding input quantity. 

2.4.5.2 Intrinsic error [VIM:1993, 5.24 [1]] 

Error of an instrument determined under reference conditions. 

2.4.5.3 Initial intrinsic error 

Intrinsic error of an instrument as determined prior to performance tests. 

2.4.5.4 Maximum permissible error, MPE [VIM:1993, 5.21 [1]] 

Extreme value of an error permitted by specifications, regulations, etc., for a given instrument. 

2.4.5.5 Fault 

Difference between the error of indication and the intrinsic error of a taximeter. 

Note: Principally, a fault is the result of an undesired change of data contained in or flowing through 

the measuring instrument. In this Recommendation, a "fault" is a numerical value. 

2.4.5.6 Significant fault 

Fault, the magnitude of which is greater than the maximum permissible error of the taximeter. 

The following are not considered to be significant faults: 

 faults that result from simultaneous and mutually independent causes in the instrument; 

 faults that make it impossible to perform any measurement; 

 transitory faults that are momentary variations in the indications which cannot be interpreted; 

memorized or transmitted as a measurement result; 

 faults that are so serious that they will inevitably be noticed by those interested in the 

measurement. 

2.5 Test conditions 

2.5.1 Equipment under test (EUT) 

Taximeter or device subjected to performance tests. 

2.5.2 Influence quantity [VIM:1993, 2.7 [1]] 

Quantity that is not the measurand but which affects the result of the measurement. 

2.5.3 Influence factor 

Influence quantity having a value within the specified rated operating conditions of the EUT. 
OIML R 21: 2007 (E) 

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2.5.4 Disturbance 

Influence quantity having a value within the limits specified in this Recommendation, but outside the 

specified rated operating conditions of the EUT. 

2.5.5 Rated operating conditions [VIM:1993, 5.5 [1]] 

Conditions of use (e.g. reference conditions applicable in the IEC Standard) giving the range of values 

of the influence factors, for which the errors (of indication) of the EUT are required to be within the 

maximum permissible errors. 

2.5.6 Reference conditions [based on VIM:1993, 5.7 [1]] 

Set of reference values, or reference ranges of influence quantities prescribed for testing the 

performance of the EUT, or the inter-comparison of the results of measurements. 

2.5.7 Preconditioning 

Treatment of the EUT, with the object of removing, or partly counteracting, the effects of its previous 

history. Where called for, it is the first process in the test procedure. 

2.5.8 Conditioning 

Exposure of the EUT to an environmental condition (influence factor or disturbance) in order to 

determine the effect of such a condition on it. 

2.5.9 Recovery 

Treatment of the EUT, after conditioning, in order that the properties of the EUT may be stabilized 

before measurement. 

2.5.10 Performance test 

Test intended to verify whether the EUT is capable of accomplishing its intended functions. 

2.5.11 Function test 

Test conducted at ambient environmental conditions of the type evaluation test to check the distance 

and time accuracy and functionality of the taximeter. 

2.5.12 Function control test 

Test conducted during and/or after each influence factor and disturbance test to check the distance and 

time accuracy of the taximeter. 
OIML R 21: 2007 (E) 

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2.6 Symbols, units and abbreviations 

I Indication 

MPE Maximum permissible error 

EUT Equipment Under Test 

sf Significant fault 

k Number of pulses per kilometre traveled received by a taximeter 

Unom Nominal voltage value marked on the instrument 

Umax Highest value of a voltage range marked on the instrument 

Umin Lowest value of a voltage range marked on the instrument 

e.m.f Electromotive force 

I/O Input / Output ports 

RF Radio frequency 

V/m Volts per metre 

kV kilovolt 

DC Direct current 

MHz Megahertz 

Pulses/km Pulses per kilometre 

ASD Acceleration spectral density 

3 METROLOGICAL REQUIREMENTS 

3.1 Main function of the taximeter 

A taximeter shall be designed to measure the duration, and calculate the distance of a fare-paying 

journey based on a signal delivered by a distance measurement transducer. 

A taximeter displays the fare to be paid on the basis of the initial fare registered on the taximeter 

before distance is traveled and the fare incrementing with fixed intervals after the appertaining 

distance and/or time is delivered. 

3.2 Maximum permissible errors (MPE) 

3.2.1 Initial verification 

The maximum permissible errors, plus or minus, on initial verification: 

3.2.1.1 For a taximeter not installed in the vehicle: 

(a) For the elapsed time, 0.2 s or 0.1 % whichever is greater; 

(b) For the distance traveled, 4 m or 0.2 % whichever is greater; 

(c) For the fare calculated, 0.1 %. Allowance shall be made for the rounding of the least significant 

digit of the fare indication. 

3.2.1.2 For a taximeter installed in the vehicle: 

(a) For the elapsed time, 0.2 %; 

(b) For the distance traveled, 2 %; 
OIML R 21: 2007 (E) 

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(c) Adjust the taximeter constant, k, to the vehicle on which the taximeter is mounted as close as 

possible to zero error where applicable compensating for wear and tear of the tires of the vehicle. 

3.2.2 In-service verification 

The maximum permissible errors on in-service verification of a taximeter shall be as specified in 

3.2.1.2 for vehicle-installed taximeters. 

3.3 Taximeter accuracy conformance over time 

A taximeter system shall be designed so that it can conform to the maximum permissible errors 

without adjustment for a period of not less than one year of normal use and in accordance with 

national regulations. Any malfunction of the taximeter arising from significant faults shall be 

automatically and clearly indicated (e.g. by a visible or audible fault indication or by automatic switch 

off). The documentation submitted by the manufacturer (6.2.1) shall include a description of how this 

requirement is met. 

3.4 Units of measurement 

The units of measurement to be used on a taximeter are: 

 time, in seconds, minutes and hours; 

 distance, in metres (m) or kilometres (km), or as specified in national regulations; 

 the fare with the monetary unit, as specified in national regulations. 

3.5 Variations due to influence quantities 

An instrument shall comply, unless otherwise specified and as far as applicable, with 3.2 and 3.3 under 

the conditions of 3.5. If not otherwise specified, tests shall not be combined. 

3.5.1 Temperature 

A taximeter shall maintain its metrological properties within a nominal temperature range of – 25 °C 

to + 55 °C. There shall be a minimum temperature range of 80 °C with values to be chosen from lower 

limits of – 40 °C, – 25 °C, or – 10 °C, and upper limits of + 40 °C, + 55 °C, or + 70 °C. 

3.5.2 DC voltage supply 

A taximeter shall maintain its metrological and technical requirements if the supply voltage varies 

from the lower and upper limits (Umin, Umax) of the nominal voltage supply for: 

(a) 12 V road vehicle battery voltage supply: lower limit is 9 V, upper limit is 16 V, 

(b) Other battery voltage supply specified by manufacturer with given lower and upper limits. 

A taximeter shall either continue to function correctly if there is a temporary voltage drop below the 

lower operating voltage limit or abort an existing measurement if the voltage drop is for a longer 

period (5.2.5). 

3.6 Taximeter constant, k

It shall be possible to adjust the taximeter constant, k, to the vehicle within the maximum permissible 

error of 3.2.1.1 (c). It shall be possible to display the taximeter constant, k, on the taximeter as a 

readily accessible decimal number. Every change of the taximeter constant, k, shall be secured in 

accordance with 4.2.5. The use of the taximeter shall not be possible when the change registration 

capacity is exceeded. That capacity will be defined by the manufacturer. 
OIML R 21: 2007 (E) 

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3.7 Real-time clock 

The real-time clock shall keep track of the time of the day and the date. One or both values may be 

used for the automatic change of tariffs. The following requirements apply: 

(a) The timekeeping accuracy shall be 0.02 % of the time; 

(b) The correction possibility of the clock shall be not more than 2 minutes per week. Correction for 

summer and winter time shall be performed automatically in applicable countries and shall be 

secured in accordance with 4.2.5; 

(c) Other time corrections, automatic or manual, shall be prevented during a journey, unless 

conducted during a verification process. 

In the event of an interruption of the power, the real time clock shall continue to function correctly, 

and retain the correct time and date in the taximeter for at least one year, unless otherwise specified in 

national regulations. 

4 TECHNICAL REQUIREMENTS 

4.1 Suitability for use 

A taximeter shall be designed to suit the method of operation and vehicles for which it is intended. It 

shall be of adequately robust construction in order that it maintains its metrological characteristics. 

4.2 Security of operation 

4.2.1 Fraudulent use 

A taximeter shall have no characteristics likely to facilitate its fraudulent use. 

4.2.2 Accidental breakdown and maladjustment 

A taximeter shall be so constructed that an accidental breakdown or maladjustment of devices likely to 

disturb its correct functioning cannot take place without its effect being evident (e.g. by appropriate 

securing, visible or audible fault indication or automatic switch off). 

If required by national regulations, the absence or improper functioning of connected instruments shall 

automatically prevent the operation of the taximeter. This setting of the taximeter shall be secured in

accordance with 4.2.5. 

4.2.3 Inspection and adjustment 

A taximeter shall be designed in such a way as to permit easy inspection and adjustments of the 

taximeter in order to assess its functionality and to conform to changes in its functions imposed by 

national regulations. Access to inspection and adjustment functions shall be secured in accordance 

with appropriate parts of 4.2.5. 

4.2.4 Controls and keys 

Controls and keys on taximeters effecting measurements shall be so designed that they cannot 

normally come to rest in positions other than those intended by design, unless during the manoeuvre 

all indication is made impossible. Keys shall be marked unambiguously. Controls shall be secured in 

accordance with appropriate parts of 4.2.5. 
OIML R 21: 2007 (E) 

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4.2.5 Securing of functions, hardware, software and pre-set controls 

Means shall be provided for securing taximeter functions, measurement data, hardware, software and 

pre-set controls, to which access, adjustment or removal is prohibited. Security should be provided on 

all parts of the measuring system which cannot be sealed in any other way against operations liable to 

affect the measurement accuracy. 

In accordance with national regulations there shall be adequate security to ensure that: 

(a) Any device for changing the parameters of legally relevant measurement data, particularly for 

correction and adjustment, shall be secured by appropriate hardware or software means against 

unintentional and accidental changes; 

(b) Access to legally relevant functions shall be restricted to the metrological authority, e.g. by 

hardware and/or software means such as a special device (hard key, identity scanner, etc.); 

(c) It shall be possible for the interventions to be recorded by means of an audit trail (2.3.6) or an 

event counter (2.2.3) and it shall be possible to access and display this information; the records 

shall include the date and a means of identifying the authorized person making the intervention 

(see b) above); the traceability of the interventions shall be assured for at least the period of time 

in between periodical verifications depending on national regulations; 

(d) Records may not be overwritten, and if the storage capacities for records is exhausted, no further 

intervention shall be possible without breaking a physical seal; 

(e) Software protection (2.2.8.5) against intentional, unintentional and accidental changes shall be 

provided in accordance with the requirements of 4.11; 

(f) Means of detecting physical tampering or removal of taximeter hardware shall be provided; 

(g) Transmission and updating of legally relevant measurement data and software shall be secured 

against intentional, unintentional and accidental changes in accordance with the appropriate 

requirements of 4.10, 4.11 and 5.2.3 respectively;

(h) The securing possibilities available in a taximeter shall be such that separate securing of tariff data

is possible;

(i) The securing possibilities available in a taximeter may be such that separate securing of the 

settings is possible.

4.3 Fare calculation 

The interval of fare to pay, the fare calculation method in use, and the monetary symbols shall comply 

with national regulations. 

A taximeter shall be able to calculate the fare by both of the following calculation methods, with the 

possibility to choose between these calculation methods by a secured setting: 

(a) Normal calculation method S (single application of tariff) 

The fare is calculated from time-counting below the cross-over speed and from distance-counting 

above the cross-over speed in accordance with the selected tariff. 

(b) Normal calculation method D (double application of tariff) 

The fare is calculated from combined time-counting and distance-counting in accordance with the 

selected tariff. 

The indications for fare calculation shall comply with the requirements of 4.9.1. 
OIML R 21: 2007 (E) 

19 

4.4 Tariff programming 

4.4.1 Tariffs 

Each allocated tariff includes the following values: 

 initial hire fee; 

 initial time; 

 initial distance; 

 time-tariff value; 

 distance-tariff value; 

 supplementary charge increment, if appropriate. 

4.4.2 Input of tariffs 

It shall be possible to secure the access to the level at which tariffs can be changed in accordance with 

4.2.5. 

The tariffs may be entered individually via appropriate protective user interface(s). 

Unauthorized or unintentional tariff re-programming due to interfacing with other equipment shall be 

secured in accordance with 4.2.5. 

If the taximeter is capable of having its tariffs re-programmed in advance of the effective date, those 

tariffs shall not become effective until that date. 

Where applicable, the tariffs shall have identifications and signatures of the corresponding tariff 

parameters. 

4.5 Operating position device 

The operating position device (2.2.11) is used to bring the taximeter into the operating positions 

specified below for the tariff based measurement results allocated to individual registers in the 

taximeter. 

4.5.1 “For Hire” (Free) operating position 

In the “For Hire” (Free) operating position the fare calculation is disabled (i.e. time-counting and 

distance-counting are inactive). 

In switching to the “For Hire” (Free) operating position, the fare indication and the supplement 

indication shall be cleared. 

In the “For Hire” (Free) operating position it shall be possible to display, when relevant, the following 

information: 

(a) All elements of the indicator display; 

(b) The contents of totalizers (see 4.7); 

(c) The taximeter constant, k, expressed in pulses per kilometre; 

(d) The contents of the event counters (see 4.2.5, 4.11.2); 

(e) The values of each allocated tariff (see 4.4.1); 

(f) Signatures of the corresponding tariff values; 

(g) Date and time; 

(h) Software version number and/or checksum (see 4.11.1). 

The above information shall not be displayed for more than 10 seconds when the taxi is moving, they 

shall not be interpreted as fare or supplement indication; and their use shall comply with the security 

of operation requirements of 4.2. 
OIML R 21: 2007 (E) 

20 

Other indications in the “For Hire” (Free) operating position are permitted provided that they are in 

accordance with national regulation, they shall not be interpreted as fare or supplement indication and 

their use is subject to the requirements of 4.2. 

4.5.2 “Hired” (Occupied) operating position 

In the “Hired” (Occupied) operating position the fare calculation takes place on the basis of a possible 

initial charge and a tariff for distance traveled and/or duration of the journey (i.e. time-counting and 

distance-counting are active). 

The indications in the “Hired” (Occupied) operating position at the beginning of the journey shall be 

in the following order: 

(a) The initial charge; 

(b) The first fare indication, followed by subsequent fare indication changes corresponding to the 

initial and then successive equal time intervals or distances specified in the applied tariff. 

Indications in “Hired” (Occupied) operating position may also include the distance and time displays, 

provided that they comply with the quality of indication requirements of 4.9.1 and, where appropriate, 

comply with national regulations. 

4.5.3 “Stopped” (To Pay) operating position 

In the “Stopped” (To Pay) operating position the fare calculation based on time is disabled (i.e. timecounting is inactive). The indications in “Stopped” (To Pay) operating position shall include the 

following: 

(a) The fare to be paid for the journey; or 

(b) If there is a supplementary charge for an extra service, entered by manual command, this shall be 

displayed separately from the indicated fare. However, in this case a taximeter may temporarily 

indicate the value of the fare including the supplementary charge. 

In the case of b) the indication of the supplement shall be made by figures with a height not more than 

that of the figures indicating the fare. 

The indications in the “Stopped” operating position shall comply with the requirements of 4.9.1. 

4.5.4 “Measure” operating position for the normal calculation method D (double application of 

tariff) system 

If the fare calculation is according to the normal calculation method D, the taximeter may be equipped 

with the “Measure” operating position in which the distance and duration of the journey are measured 

and displayed in real time on a separate indicator as follows: 

(a) Time measured in hours with the smallest increment of 30 seconds; 

(b) Distance measured shall have a resolution better than or equal to 0.1 km; 

(c) Readings for both time and duration may be given at the same time, or may be recalled one after 

the other by means of the operating position device; 

(d) The period of use shall be shown as hh:mm:ss and the indicated unit of measurement shall comply 

with the requirements of 4.9.1 so that there can be no confusion as to the quantity indicated. 

4.6 Additional requirements for the operating position device 

The operating position device is subject to the following requirements: 
OIML R 21: 2007 (E) 

21 

(a) In the “Stopped” (To Pay) operating position, the indication of the fare shall be readable for at 

least 10 seconds. During this period it shall not be possible to change to the “For Hire” (Free)

operating position; 

(b) The design and setting of the operating position device shall ensure that any change in operating 

positions and their indications comply with the appropriate securing requirements of 4.2.5 and 

4.9.1; 

(c) It shall not be possible to switch the operating position device to any other operating positions 

other than those mentioned above, unless otherwise specified in national regulations. 

4.7 Totalizers 

A taximeter shall be fitted with non-resettable totalizers which can clearly and unambiguously display 

all of the following values: 

(a) Total distance traveled by the taxi; 

(b) Total distance traveled when hired; 

(c) Total number of journeys; 

(d) Total amount of money charged as supplements; 

(e) Total amount of money charged as fare. 

Other data may be totalized and indicated provided that they comply with national regulations and 

with the requirements of 4.9.1 for quality of indication to prevent the display of totalized values being 

used to deceive passengers. 

Values saved under conditions of power loss shall be included in the total and shall be stored for at 

least one year for subsequent use or for a period in accordance with national regulations. In all cases 

the requirements for data storage given in 4.10 apply. 

Totalized values shall be displayed for a maximum of 10 seconds, or for a time specified in 

accordance with national regulations. 

Totalizers shall have a minimum number of digits (e.g. 8 digits) in accordance with national 

regulations. 

4.8 Automatic change of tariffs 

The automatic change of tariffs may be triggered by the: 

(a) Distance of the journey; 

(b) Duration of the journey; 

(c) Time of day; 

(d) Date; 

(e) Day of the week; or 

(f) Other data specified in accordance with national regulation. 

Any alteration of tariff values shall be secured in accordance with 4.2.5.

4.9 Indicating and printing 

4.9.1 Quality of reading 

The primary indications shall be by means of a display. Reading of the primary indications (2.4.3) 

shall be reliable, easy and unambiguous under conditions of normal use including in daylight and at 

night, and the figures forming the indications shall be of a height equal to or higher than 10 mm or of a 

size in accordance with national regulations, and of a shape and clarity that permits easy reading. 

Primary indications shall contain names or symbols of the units of measurement and comply with the 
OIML R 21: 2007 (E) 

22 

requirements of 3.4. 

The indicator display shall be so designed that the indications of interest to the passenger are sufficient 

for a particular application, suitably identified and readable from a distance of at least 2 metres. 

A digital indication shall show at least one figure beginning at the extreme right to adequately 

differentiate subordinate digits. 

A decimal fraction value shall be separated from its integer by a decimal sign (comma or dot), with the 

indication showing at least one figure to the left of the decimal sign and all figures to the right of the 

decimal sign. 

4.9.2 Printing 

In accordance with national regulations, a printer may be used to obtain a hard copy, e.g. of the results 

at the end of the measurement, audit trail record of changes to measurement features and parameters, 

etc. Printing shall be clear and permanent for the intended use. Printed figures shall be at least 2 mm in 

height, clear, legible and unambiguous. 

If printing takes place, the name or the symbol of the unit of measurement shall be either to the right 

of the value or above a column of values, or placed in accordance with national regulation. 

Multiple copies of the print-out containing the same data must be marked “copy” or “duplicate”. 

The minimum printout resulting from each measurement operation shall be dependent upon the 

application of the taximeter in accordance with national regulations. In general the printout 

information may include the following: 

 tariff identification; 

 fare; 

 supplementary charge; 

 distance and duration of the journey; 

 date and the time of the journey; 

 taxi identification number. 

4.10 Data storage 

Legally relevant data stored in a memory of the taximeter or on external storage (e.g. hard-drive) for 

subsequent legal use shall be adequately protected against intentional and unintentional changes 

during the storage and data transmission process. 

In accordance with national regulations there shall be adequate security to ensure that: 

(a) Securing of legally relevant software stored or transmitted between storage devices comply with 

the appropriate requirements of 4.11; 

(b) The legally relevant measurement data stored or transmitted shall be accompanied by all relevant 

information necessary to reconstruct an earlier measurement for future legally relevant use; 

(c) External storage device identification and security attributes shall be verified to ensure integrity 

and authenticity; 

(d) Exchangeable storage media is sealed against unauthorized removal in accordance with 4.2.5; 

(e) For long term storage of legally relevant data, the data must be stored automatically when the 

measurement is concluded. The long-term storage must have a capacity which is sufficient for the 

intended use; 

(f) When the storage is full, new data may replace oldest data provided that the owner of the old data 

has given authority to overwrite the old data and it complies with the appropriate requirements of 

4.2.5 and 4.11. 
OIML R 21: 2007 (E) 

23 

4.11 Software 

There shall be a distinct separation between the legally relevant and non-relevant software (2.2.8.6) in 

a taximeter. The legally relevant software of a taximeter shall be identified by the manufacturer, i.e. 

the software that is critical for measurement characteristics, measurement data and metrologically 

important parameters, stored or transmitted, and software programmed to detect system faults 

(software and hardware), is considered as an essential part of a taximeter and shall meet the 

requirements for securing software specified below. National regulations may specify the security that 

is required. 

4.11.1 In accordance with national regulations software documentation submitted with the 

instrument shall include: 

(a) A description of the legally relevant software; 

(b) A description of the accuracy of the measuring algorithms (e.g. rounding algorithm when 

calculating the distance or price); 

(c) A description of the user interface, menus and dialogues; 

(d) The unambiguous software identification; 

(e) An overview of the software system; 

(f) Means of securing software; 

(g) The operating manual; 

(h) Other information relevant to the software characteristics of the taximeter. 

4.11.2 In accordance with national regulations there shall be adequate security to ensure that: 

(a) The legally relevant software shall be adequately protected against accidental or intentional 

changes by means of an audit trail (2.3.6) or an event counter (2.2.3) providing information record 

of the changes to the software; 

(b) The legally relevant software shall be assigned with a software identification (2.2.8.4) which shall 

be adapted in the case of every software change that may affect the functions and accuracy of the 

taximeter. Software identification shall be easily provided by the taximeter; 

(c) The transmission, changing and updating of the legally relevant software shall be secured, e.g. 

through the use of protective interfaces connected to the taximeter, and comply with the relevant 

requirements and conditions of 5.2.3; 

(d) It shall be possible to access and display the information in the audit trail records; the records shall 

include the date and a means of identifying the authorized person making the intervention (see (a) 

above); the traceability of the interventions shall be assured for at least the period of time in 

between periodical verifications depending on national legislation. Legally relevant records may 

not be overwritten, and if the storage capacities for legally relevant records are exhausted, no 

further intervention shall be possible without breaking a physical seal. 

4.12 Descriptive markings 

Taximeters shall bear the following markings, variable according to national regulations: 

 name or identification mark of manufacturer; 

 name or identification mark of the importer (if applicable); 

 serial number of the taximeter (if applicable); 

 type approval sign and/or number of type examination certificate; 

 relevant data in respect of the conditions of use; 

 year of manufacture; 

 specified range of the taximeter constant, k, (if applicable) in pulses per kilometre; 

 software identification (if applicable). 
OIML R 21: 2007 (E) 

24 

4.12.1 Supplementary markings 

Depending upon the particular use of the taximeter, one or more supplementary markings may be 

required, e.g.: 

 relevant data in respect of the conditions of use; 

 where a particular taximeter is verified using a particular type of vehicle (i.e. air suspension 

systems only). 

4.12.2 Presentation of descriptive markings 

Descriptive markings shall be indelible and of a size, shape and clarity that permit legibility under 

normal conditions of use of the instrument. Markings shall be grouped together in a clearly visible 

place on the instrument, either on a descriptive plate fixed near the indicating device or on the 

indicating device itself. It shall be possible to seal the plate bearing the markings, unless it cannot be 

removed without being destroyed. 

These additional markings may be either in the national language or in form of adequate, 

internationally agreed and published pictograms or signs. 

The descriptive markings in 4.12 may be simultaneously displayed by a software solution, either 

permanently or on manual command. In this case the markings are considered as device-specific 

parameters (see 2.2.8.3), and the following shall apply: 

 the taximeter constant, k, and the date shall be displayed as long as the taximeter is switched 

on; 

 the other markings may be accessed and displayed by a simple manual command (e.g. a 

specific keystroke); 

 it shall be described in the type approval certificate; 

 such markings shall be secured in accordance with the securing requirements given in 4.2.5 

and 4.11.2. 

The software controlled display markings need not be repeated on the data plate, if they are shown on 

or indicated near the display of the measurement result, with the exception of the following markings 

which shall be shown on the data plate: 

 k and the date shall be shown on the display; 

 type approval sign in accordance with national requirements; 

 name or identification mark of the manufacturer. 

4.13 Verification marks 

According to national regulations, initial verification may be testified by verification marks, e.g.: 

 verification authority identification; 

 date of verification; 

 other verification markings specified in accordance with national regulations (e.g. actual value 

of the taximeter constant, k, in pulses per kilometre, vehicle registration, taximeter serial 

number). 

After every subsequent verification new marks shall replace the old marks where necessary to reflect 

new information. 

4.13.1 Position of verification marks 

A place shall be provided for the application of verification marks. This place shall: 

 be such that the part on which the marks are located cannot be removed from the taximeter 

without damaging the marks; 
OIML R 21: 2007 (E) 

25 

 permit the easy application of the marks without changing the metrological qualities of the 

taximeter; 

 be clearly and visibly marked on, in or near the fare indicating device when the taximeter is in 

service. 

4.14 Installation and test conditions 

4.14.1 General 

Taximeters shall be manufactured, tested and installed so as to minimize any adverse effects of the 

testing and installation environment. If the correct testing or operation of the taximeter is likely to be 

affected by the properties of other connected equipment and the vehicle in which it is installed, then 

the taximeter shall be provided with a means to secure the correct testing and operation of the 

taximeter (e.g. a test connector interface as specified in 5.2.3 for testing purposes). Where particular 

details of installation have an effect on the accuracy of the taximeter these details shall be recorded in 

the test report (e.g. influence of the vehicle) and in the operating and installation manual of the 

taximeter. 

4.14.2 Taximeter operation 

After installation the taximeter shall comply with the appropriate requirements of this 

Recommendation. 

All settings that can influence the taximeter compliance with the requirements of this 

Recommendation shall be secured (see 4.2.5), with access possible only through a special secure 

mode, e.g. a service mode (2.3.8). Other settings not subject to legal control shall have appropriate 

protected access (see 4.2.5) through e.g. an operational mode (2.3.7). 

5 ELECTRONIC REQUIREMENTS 

5.1 General requirements 

Taximeters shall comply with the following requirements in addition to the applicable requirements of 

all other clauses of this Recommendation. 

5.1.1 Rated operating conditions 

Taximeters shall be so designed and manufactured that they do not exceed the maximum permissible 

errors under rated operating conditions. 

5.1.2 Influence quantities 

In addition to 3.5, an electronic instrument shall comply with the requirements under a relative 

humidity above 93 % when combined with cyclic temperature changes and condensation. 

5.1.3 Disturbances 

Taximeters shall be so designed and manufactured that when exposed to disturbances, either: 

(a) Significant faults do not occur (i.e. the difference between the indication due to the disturbance 

and the indication without the disturbance (intrinsic error), either shall not exceed the value given 

in 2.4.5.6; or 

(b) Significant faults are detected and acted upon. The indication of significant faults in the display 

should not be confusing with other messages that appear in the display. 
OIML R 21: 2007 (E) 

26 

5.1.4 Durability 

The requirements of 5.1.1, 5.1.2 and 5.1.3 shall be met durably in accordance with the intended use of 

the instrument. 

5.1.5 Evaluation for compliance 

A type of a taximeter is presumed to comply with the requirements of 5.1.1, 5.1.2, 5.1.3 if it passes the 

examination and tests specified in Annex A. 

5.1.6 Application 

The requirements of 5.1.3 may be applied separately to each: 

(a) Individual cause of significant fault; and/or 

(b) Part of the measuring instrument. 

The choice of whether 5.1.3 (a) or (b) is applied is left to the manufacturer. 

5.2 Functional requirements 

5.2.1 Indicator display test 

Upon switch-on (of indication), a display test procedure shall be performed that shows all relevant 

signs of the indicator in their active and non-active state sufficiently long to be checked by the 

operator. This is not applicable for non-segmented displays, on which failures become evident, for 

example, screen-displays, matrix-displays, etc. 

5.2.2 Acting upon significant faults 

When a significant fault has occurred, either the taximeter shall be made inoperative automatically, or 

a visual or audible indication shall be provided automatically and shall continue until the user takes 

action or the fault disappears. 

5.2.3 Interfaces 

A taximeter shall be equipped with interfaces (see 2.2.5) permitting the coupling of the taximeter to 

any other instruments or the vehicle for automatic transmission of information, and a user interface 

(2.2.6) permitting the exchange of information between a human user and the taximeter. 

A taximeter shall be able to transmit the following data through appropriate protective interfaces: 

 operation position: “For Hire”, “Hired” or “Stopped”; 

 totalizer data according to 4.7; 

 general information: constant of the distance measurement transducer, date of securing, 

vehicle identification, real time, tariff identification; 

 fare information for a journey: total charged, fare, calculation of the fare, supplement charge, 

date, start time, finish time, distance traveled; 

 appropriate tariff(s) information: parameters of tariff(s). 

5.2.3.1 In accordance with national regulations documentation on interface submitted with the 

instrument shall include: 

(a) Description of the interface and identification (e.g. RS232, USB, interface number or label, etc.); 

(b) A list of all commands (e.g. menu items in case of a user interface or commands accepted by the 

software of the device, received via each communication interface); 
OIML R 21: 2007 (E) 

27 

(c) A brief description of their meaning and their effect on the functions and data of the measuring 

instrument; 

(d) Other relevant information regarding the interface characteristics of the taximeter. 

5.2.3.2 Securing of interfaces 

An interface through which the functions mentioned in 5.2.3 cannot be performed or initiated, need 

not be secured. 

For other interfaces and in accordance with national regulations there shall be adequate security to 

ensure that: 

(a) Interfaces shall not allow the metrological functions of the taximeter and its legally relevant 

software and data to be inadmissibly influenced by other interconnected instruments, or by 

disturbances acting on the interface; 

(b) The legally relevant data and metrological functions are protected against accidental or intentional 

changes by a protective interface; 

(c) The legally relevant functions in the taximeter’s interfaces shall be subject to the appropriate 

requirements for securing hardware in 4.2.5 and software in 4.11; 

(d) The legally relevant parts of the connected instrument, and functions performed or initiated by the 

connected instrument shall be included in the initial or subsequent verification; 

(e) It shall be easily possible to verify the authenticity and integrity of data transmitted to and/or from 

the taximeter and the connected instrument. 

5.2.4 Taximeter test connector 

Where the accuracy of the taximeter is to be determined through the functional testing described in 

A.4, the taximeter shall have a test connecter that is capable of processing at least the signals in 

Table 1. The functioning of this test connector shall be checked once to ensure that it is capable of 

processing the signals in Table 1. 

Table 1 – Taximeter test connection signals 

Input: Output: 

Distance pulses at a rate equivalent to a speed 

of up to 200 km/h Distance pulses 

Time pulses at a rate equivalent of up to 10 

times real time Time pulses 

Signal to block time counting A signal to indicate fare increments. 

The electrical data of the signals must be compatible with the following: 

Signal LOW (logic 0) – 12 V < UI < 0.8 V Signal LOW (logic 0) 0 V< UI < 1 V (1)

Signal HIGH (logic 1) 3 V < Uh < 12 V Signal HIGH (logic 1) 3 V< Uh < 5 V (1)

Input resistance, R > 4.7 kΩ Source resistance, Rs < 10 kΩ(1)

Notes: 

(1) No load at test pin. 

(2) Signals are referred to ground on the test connector, normally the negative line of 

the taximeter supply voltage. 

(3) All signals shall be of rectangular shape with a pulse width of at least 25 μs and a 

rise and fall time of a maximum of 20 % of the pulse width. 

The taximeter test connector shall be easily accessible after installation in a vehicle provided that it is 

secured against unauthorized access in accordance with 4.2.5. 
OIML R 21: 2007 (E) 

28 

If the taximeter is connected to a network in the car (e.g. CAN bus), there shall be the possibility for 

an input and output for the distance information. In that case the taximeter does not work with pulses 

but with digital distance information. 

5.2.5 Voltage drop below the lower operating voltage limit (3.5.2) 

In case of a voltage drop below the lower operating voltage limit, the taximeter shall automatically: 

(a) Continue to function correctly or resume its correct functioning without loss of data available 

before the voltage drop if the voltage drop is temporary (e.g. less than 20 seconds), for example 

due to restarting the vehicle engine; 

(b) Abort an existing measurement and return to the “For Hire” (Free) operating position if the 

voltage drop is for a longer period (e.g. greater than 20 seconds). In this case, the taximeter shall 

resume its correct functioning and the stored measurement data concerning the aborted journey 

must be correct; 

(c) Show a significant fault or is automatically put out of service if the voltage drop is for a lengthy 

period. 

If disconnected from the supply voltage, a taximeter shall store the totalized values for at least one 

year or for a period set in accordance with national regulations. 

5.2.6 Repeatability 

The application of the same taximeter under the same conditions of measurement shall result in the 

close agreement of successive measurements. The difference between the successive measurement 

results shall be less than the appropriate maximum permissible error in 3.2. 

5.3 Examination and tests 

The examination and testing of a taximeter and any devices having metrological influence is intended 

to verify compliance with the applicable requirements of this Recommendation. 

5.3.1 Examination 

A taximeter having metrological influence shall be examined to obtain a general appraisal of the 

design and construction. 

Devices may be examined and tested only once while being connected to a taximeter, and may be 

declared as suitable for connection to any verified taximeter having an appropriate and protective 

interface. 

A description of the operation and type of devices fitted to the taximeter shall be included in the type 

approval certificate. 

5.3.2 Performance tests 

A taximeter shall be tested as specified in Clause 7 and Annex A to determine the correct functioning 

of the equipment. 

Susceptibility that would result from the use of electronic interfaces to other equipment shall be 

determined in the tests. 
OIML R 21: 2007 (E) 

29 

5.3.3 Metrological features to be considered 

All metrologically relevant features and functions (see 3, 4 and 5) have to be tested at least once in a 

taximeter as far as applicable and as many as possible in the same taximeter. Variations in 

metrologically relevant features and functions such as different housings, temperature and humidity 

ranges, instrument functions, indications, etc. may require additional partial testing of those factors 

which are influenced by that feature. These additional tests should preferably be carried out on the 

same taximeter, but if this is not possible, tests on one or more additional taximeter may be performed 

under the responsibility of the testing authority. 

6 METROLOGICAL CONTROLS 

6.1 General 

The metrological controls of taximeters shall, in agreement with national regulations, consist of: 

 type approval; 

 initial verification; 

 subsequent verification; 

 in-service inspection. 

Tests should be applied uniformly by the legal metrology services and should form a uniform 

program. Guidance for the conduct of type approval and initial verification is provided in OIML 

International Documents D 19 [5] and D 20 [6] respectively. 

6.2 Type approval 

6.2.1 Documentation 

The application for type approval shall include the submission to the metrological authority of the 

following information and documents, as far as applicable and in accordance with national regulations: 

 metrological characteristics of the taximeter (3); 

 technical and electronic specifications (4, 5); 

 functional description of the taximeter and its devices (2.3, 3.1, 5.2); 

 drawings, diagrams, and photos of the instrument explaining its construction and operation; 

 description and application of securing components, controls, fault indication function, etc. 

(3.2, 4.10, 5.2); 

 interfaces (types, intended use, immunity to external influences instructions (4.2.5, 5.2.3); 

 general software information (4.11, 4.12.2); 

 printing devices (4.9.2); 

 data storage devices (4.10); 

 drawing or photo of the instrument showing the principle and the location of control marks, 

securing marks, descriptive and verification marks (4.2.5, 4.12); 

 list of tariffs provided on the taximeter (4.4); 

 any document or other evidence that the design and construction of the taximeter and devices 

comply with the requirements of this Recommendation; 

 operating instructions, operating manual. 

Note: Adherence to requirements for which no test is available, such as software-based operations, 

may be demonstrated by a specific declaration of the manufacturer (e.g. for interfaces as per 

5.2.3, and for protected access to setup and adjustment operations as per 4.2.5. 
OIML R 21: 2007 (E) 

30 

6.2.2 Type evaluation 

Type evaluation shall be carried out on one or more taximeters submitted in a form suitable for 

laboratory tests. The submitted documents shall be examined and tests carried out to verify that the 

taximeter complies with the: 

(a) Metrological requirements in Clause 3, particularly with reference to the appropriate limits of 

error and the operating conditions specified by the manufacturer; 

(b) Technical requirements in Clause 4; and 

(c) Electronic requirements in Clause 5. 

The appropriate metrological authority shall conduct the tests in a manner that prevents an 

unnecessary commitment of resources, and that permits the results of the tests to be assessed for initial 

verification. 

The appropriate metrological authority may: 

(a) Conduct other appropriate tests in accordance with national regulations to verify compliance with 

the metrological and technical requirements of this Recommendation; 

(b) Accept, with the consent of the applicant, test data obtained from other metrological authorities 

without repeating tests. 

6.2.2.1 Type evaluation tests 

Type evaluation tests shall be performed under the normal rated operating conditions for which the 

taximeter is intended. The functioning of the taximeter shall be determined as specified in Clause 7 

and Annex A, and influence factors shall be applied to the taximeter as specified in 3.5 and Annex A. 

Type evaluation tests shall be performed either on the premises of the metrological authority to which 

the application has been submitted, or in any other suitable place agreed between the metrological 

authority concerned and the applicant. 

The metrological authority may require the applicant to supply equipment and personnel to perform 

the tests. 

6.2.2.2 Type approval certificate 

The following information shall appear on the type approval certificate: 

 name and address of the recipient of the certificate; 

 name and address of the manufacturer, if not the recipient; 

 type of the instrument and number of the certificate number; 

 metrological and technical characteristics; 

 type approval mark; 

 information on the location of marks for type approval, initial verification and securing; 

 list of documents accompanying the type approval certificate; and 

 specific remarks. 

If applicable, the version of the metrological part of the evaluated software shall be indicated in the 

type approval certificate or its annexes. 

6.2.2.3 Determination of accuracy requirements 

Accuracy requirements shall be determined in accordance with the appropriate parts of 3.2.1 by 

compliance with the metrological requirements at initial verification of the taximeter. 
OIML R 21: 2007 (E) 

31 

6.3 Initial verification 

6.3.1 General requirements 

Initial verification tests shall be carried out in accordance with national regulations by the appropriate 

metrological authority. 

The appropriate metrological authority shall conduct the tests in a manner that prevents an 

unnecessary commitment of resources. In appropriate situations and to avoid duplicating tests 

previously performed on the taximeter for type evaluation under 6.2.2, the authority may use the 

results of observed tests for type evaluation. 

The metrological authority may require the applicant to supply equipment and personnel to perform 

the tests. 

6.3.2 Initial verification tests 

Initial verification shall not be performed unless conformity of the taximeter to the approved type 

and/or the requirements of OIML R 21 is established. 

Initial verification tests shall be carried out to verify compliance with the following: 

 appropriate maximum permissible errors in 3.2.1; 

 correct functioning of all devices, e.g. distance transducer, taximeter, real-time clock; 

 construction material and design, as far as they are of metrological relevance; 

 if appropriate, a list of the tests performed; 

 secured tariffs (if applicable, depending on national regulations). 

Tests shall be performed on the taximeter, including all devices which form the assembly as intended 

for normal operational use, and the verification procedure may be carried out in two stages, where the 

first stage shall allow for easy examination of the tariff parameters and distance measurement without 

the influence of the vehicle, and the second stage shall comprise all examinations of which the 

outcome is dependent on tests of a vehicle-installed taximeter. 

6.3.3 Visual inspection 

Before testing, the taximeter shall be visually inspected for: 

 physical metrological characteristics, i.e. measurement units, real-time clock; 

 identification of software, if applicable; 

 prescribed markings and positions for verification and control marks. 

If the location and conditions of use of the instrument are known, it should be considered whether they 

are appropriate. 

6.3.4 Marking and securing 

According to national regulations, initial verification may be testified by verification marks as 

specified in 4.13. National regulations may also require securing of devices whose dismantling or 

maladjustment might alter the metrological characteristics of the taximeter without the alterations 

being clearly visible. The provisions of 4.2.5 and 4.13 shall be observed. 

6.4 Subsequent metrological control 

Subsequent metrological control may be performed by the metrological authority according to national 

regulations. 
OIML R 21: 2007 (E) 

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6.4.1 Subsequent verification 

Subsequent verification shall be carried out in accordance with the same provisions as in 6.3 for initial 

verification with the error limits being those in 3.2.1.2 for a taximeter installed in a vehicle. Marking 

and securing may take place according to 6.3.4, the date being that of the subsequent verification. 

6.4.2 In-service inspection 

In-service inspection shall be carried out in accordance with the same provisions as in 6.3 for initial 

verification with the exception that the in-service maximum permissible errors in 3.2.1.2 shall be 

applied. Marking and securing may remain unchanged, or renewed as per 6.4.1. 

7 TEST METHOD 

7.1 General 

A taximeter shall undergo type approval in accordance with the requirements of A.1. All the relevant 

test information, indications and functional performance shall be recorded for the tests. Other tests or 

test data in accordance with 6.2.2 may be used to verify the performance of the taximeter to the 

requirements of this Recommendation. 

Initial verification of a taximeter, including all devices which form the assembly as intended for 

normal operational use, shall include checks for conformity to the approved type, and verification of 

the metrological and technical requirements in accordance with A.2 in appropriate situations and to 

avoid duplicating tests previously performed on the taximeter under type approval.

7.2 Functional tests according to the featured calculation method (A.4) 

The following functional tests are performed according to the featured calculation methods S and D in 

the taximeter and conducted in accordance with the test program in Table 2: 

(a) Function test in 7.2.1; 

(b) Function control test in 7.2.2; 

(c) Visual examination in 7.3; and 

(d) Test report format in 7.4. 

7.2.1 Function test (A.4.3) 

The function test for the featured calculation method S and D in the taximeter consists of an initial 

check of the taximeter's accuracy and is performed at the beginning of the test program (see Table 2) 

at ambient conditions and in accordance with A.4.3 for the following parameters: 

(a) Test of initial distance and initial time; 

(b) Lowest, middle and highest values of: 

(1) the specified pulse frequency range (from 5 km/h up to a maximum speed of at least 200 km/h 

as specified by the manufacturer); 

(2) pulse voltage levels; 

(3) three or more k values shall be tested (each with a minimum and maximum number of pulses 

per kilometre specified by the manufacturer); 

(c) Selection of automatic changes, if applicable (see 4.8); 

(d) Supply voltage variations. 

The start and end times, the date of the function test and the checklist for the taximeter's operation and 

tasks (see Annex C) shall be completed during the function test. 
OIML R 21: 2007 (E) 

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7.2.2 Function control test during and after influences or disturbances (A.4.4) 

Function control tests for the featured calculation method S and D in the taximeter are conducted to 

check the taximeter's accuracy for a suitable tariff during and/or after influence or disturbance 

conditions as specified in Table 2 and A.4.4. 

7.3 Visual examination (A.4.2) 

The EUT shall be carefully checked for any visible deterioration before and after each test. Details of 

observations shall be noted and recorded. 

7.4 Test report format 

The results of the tests shall be recorded in the test report format given in Annex C. 
OIML R 21: 2007 (E) 

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7.5 Program of functional tests 

Table 2 –Test program 

Test 

category Test Test reference Notes 

1 Initial visual examination and function 

test. A.4.3 Initial check of taximeter accuracy at ambient conditions. 

(a) Static temperatures function control 

tests. A.5.4.1 Function control during dry heat and cold tests. 

(b) Damp heat cyclic (condensing) 

function control tests. 2 A.5.4.2 Function control during damp heat cyclic tests. 

(c) Visual examination and function 

control test. A.4.4 

Repeat the function control test at ambient 

conditions after completion of the damp heat 

cyclic test. Check the recorded information. 

(a) Voltage supply variations function 

control test. 

A.5.4.3 Function control test during voltage variations test. 

3 

(b) Function control and visual 

examination. A.4.4 

Repeat the function control test at ambient 

conditions after completion of the voltage 

variations test. Check the recorded information. 

(a) Random or sinusoidal vibration 

function control test. 

A.5.4.4.1 

or 

A.5.4.4.2 

Function control during vibration test. 

4 

(b) Function control and visual 

examination. A.4.4 

Repeat the function control test at ambient 

conditions after completion of the random or 

sinusoidal vibrations test. Check the recorded 

information. 

(a) Immunity to radiated electromagnetic 

fields. A.5.4.5.1 

(b) Immunity to conducted electromagnetic 

fields. A.5.4.5.2 

(c) Electrostatic discharge test. A.5.4.6 

5 

(d) Visual examination and function 

control test. A.4.4 

Repeat the function control test at ambient 

environmental conditions after completion of the 

electrostatic discharges tests. Check the recorded 

information. 

(a) Electrical transient conduction along 

supply lines. A.5.4.7.1 

(b) Electrical transient conduction via 

lines other than supply lines. 6 A.5.4.7.2 

(c) Function control and visual 

examination. A.4.4 

Repeat the function control test at ambient 

conditions after completion of the test for 

electrical transient conduction via other supply 

lines. Check the recorded information. 
OIML R 21: 2007 (E) 

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Annex A (Mandatory) 

Test procedures for taximeters 

A.1 Examination for type approval (6.2) 

The following shall normally be applied for type evaluation: 

(a) Review the documentation submitted to determine whether it is adequate and correct. Consider the 

operational manual. For type approval the documentation shall be as specified in 6.2.1; 

(b) Compare construction with documentation and examine the various devices of the taximeter to 

ensure compliance with the documentation specified in 6.2.1; 

(c) Note the metrological characteristics using the checklist given in the test report format in 

Annex C; 

(d) Examine the taximeter for conformity with the technical requirements in Clause 4, in accordance 

with 6.2.2 and using the checklist given in the test report format in Annex C; 

(e) Examine the taximeter for conformity with the requirements of 5.1, 4.2 and 5.3, in accordance 

with 6.2.2 and using the checklist given in the test report format in Annex C. 

A.2 Examination for initial verification (6.3) 

(a) Examine the taximeter for conformity with the approved type and/or the requirements of this 

Recommendation in accordance with 6.3; 

(b) Check the descriptive markings in accordance with 4.12 using the checklist given in the test report 

format in Annex C; 

(c) Check the arrangement for verification marks and securing in accordance with 6.3.5 using the 

checklist given in the test report format in Annex C. 

A.3 General test requirements 

A.3.1 Supply voltage (3.5.2) 

Power up the EUT and maintain the EUT energized for the duration of each test, unless otherwise 

specified in the test. 

A.3.2 Temperature (3.5.1) 

The tests shall be performed at a steady ambient temperature unless otherwise specified. 

There shall be no condensation of water on the EUT unless otherwise specified for each test. 

A.3.3 Recovery 

After each test the EUT shall be allowed to recover sufficiently before the next test. 

A.4 Functional tests (7.2) 

A.4.1 General 

The taximeter shall be connected through its test connector to a calibrated pulse counter and a 

calibrated timer as appropriate for the functional tests. Refer to Table 1 for test connection signals 

information. 

The functional tests shall be conducted at rated operating voltage of 12 V DC for 12 V systems. 
OIML R 21: 2007 (E) 

36 

For other voltage systems the functional tests shall be conducted at the appropriate operating voltage, 

e.g. at 24 V DC for 24 V systems. 

A.4.2 Visual examination (7.3) 

The EUT shall be inspected visually before and after each functional test in the test program in 

Table 2. The registered results from the tests shall be checked. 

A.4.3 Function test (7.2.1) 

This is the first test conducted at the beginning of the test program in Table 2 to check the accuracy of 

the time (if applicable) and the distance measurement as specified in 7.2.1 and in accordance with 

Table 3. 

Table 3 - Summary of the function test 

Test conditions Measuring parameters Error allowance 

Accuracy of the time (if applicable) and the distance 

measurement: 

(a) at voltages of 9 V and 16 V 

(b) for the featured calculation method S or D 

pulse frequency levels 

pulse voltage levels 

12 V DC under 

reference ambient 

conditions 

(c) Lowest, medium and 

highest values of: 

specified k values 

maximum permissible 

error 

(see 3.2.1) 

(d) Selection of automatic changes (if applicable) 

(e) The time and date of the test (e.g. at the beginning 

and end of tests) and checklist for operation and 

tasks 

4.8 

Test report format 

(see Annex C) 

Visual examination Check recorded information and examine the taximeter 

for visual defects A.4.2 

A.4.4 Function control test (7.2.2) 

These are subsequent tests to check the accuracy of the time (if applicable) and the distance 

measurement during and after the application of influence factors and/or disturbances as specified in 

7.2.2 and in accordance with Table 4. 

Table 4 - Summary of the function control test 

Test conditions Measuring parameters Error allowance 

12 V DC under 

conditions of influences 

and disturbances 

Time (A.4.5.2) and distance (A.4.5.1) accuracy for 

calculation method S and D during influences and/or 

disturbances (see Table 2). 

After application of influences and/or disturbances (see 

Table 2): 

(a) Time and distance accuracy for calculation method 

S and D, and 

Maximum permissible 

error 

(see 3.2.1) 

12 V DC under ambient 

conditions 

(b) Visual inspection - check recorded information 

and examine taximeter for visual defects 

A.4.2 
OIML R 21: 2007 (E) 

37 

A.4.5 Function control test for calculation method S (single application of tariff) 

A.4.5.1 Distance measurement 

To eliminate the influence of time from the distance test the use of the test connection input “signal to 

block time counting” (see Table 1) is recommended for this test so that the time and distance can be 

examined separately. 

A.4.5.1.1 Test of the initial distance 

The test of the initial distance is conducted as follows: Beginning with the taximeter set to the “For 

Hire” (Free) operating position, use the pulse counter to measure the number of pulses generated 

between switching the taximeter to the “Hired” (Occupied) operating position and one fare increment 

step. The difference between this number of pulses (actual) and the number expected (reference) 

according to the programmed tariff is checked for compliance with the applicable initial verification 

maximum permissible error limits in 3.2.1 taking into consideration the distance represented by each 

pulse. 

A.4.5.1.2 Test of distance counting accuracy 

The test of distance counting accuracy can be done at a simulated speed of up to 200 km/h. When 

using this speed, it should be at least 10 fare increments. With the taximeter set to the “Hired” 

(Occupied) operating position, the two test possibilities are given below: 

(a) Use the pulse counter to measure the time elapsed for switching the taximeter for a specified 

number of fare increments. This time (actual) is then compared to the time expected (reference) 

according to the programmed tariff, and the taximeter constant, k; 

(b) A predetermined number of distance pulses calculated for a number of fare increments at the pulse 

input of the taximeter to recognize whether the taximeter displays the corresponding number of 

fare increments. Compare this number of pulses to the number of expected fare increment steps 

according to the programmed tariff and the taximeter constant, k. 

A.4.5.2 Time measurement 

A.4.5.2.1 Test of the initial time 

The test of the initial time is conducted as follows: Beginning with the taximeter set to the “For Hire” 

(Free) operating position, the timer is used to measure the number time pulses elapsed between 

switching the taximeter to the “Hired” (Occupied) operating position and one fare increment step. The 

difference between the measured time (actual) and time expected (reference) according to the 

programmed tariff is checked for compliance with the applicable initial verification maximum 

permissible error limits in 3.2.1. 

A.4.5.2.2 Test of time counting accuracy 

The test of time counting accuracy is conducted as follows: With the taximeter set to the “Hired” 

(Occupied) operating position, the pulse counter is used to measure time pulses at 10 times higher 

frequency (see Table 1) for a number of fare increments. The measured time is compared to the time 

expected according to the programmed tariff, and checked for compliance with the applicable initial 

verification maximum permissible errors in 3.2.1. 

A.4.6 Function control test for calculation method D (double application of tariff) 

The pulse counter is used to measure the number of distance pulses generated between switching the 

taximeter to the “Hired” (Occupied) operating position and one fare increment step, and at the same 
OIML R 21: 2007 (E) 

38 

time the timer is used to measure the time elapsed between switching the taximeter to the “Hired” 

(Occupied) operating position and one fare increment step. 

The difference between the number of pulses (actual) counted and the number expected (reference) 

according to the programmed tariff, and the difference between the time measured (actual) and the 

time expected (reference) according to the programmed tariff are checked for compliance with the 

applicable initial verification maximum permissible error limits in 3.2.1, taking into consideration the 

distance represented by each pulse. 

A.5 Performance tests 

A.5.1 General test conditions 

Metrological performance tests are intended to verify that taximeters can function as intended in the 

climatic, mechanical and electromagnetic environments and under the conditions specified. Each test 

indicates, where appropriate, the reference condition under which the intrinsic error is determined. 

Where possible, tests shall be carried out on a taximeter in its normal operational state under 

laboratory conditions. The permissible effects of the influence factors or disturbances, under these 

laboratory conditions, are specified for each test in Annex A. 

When the effect of one influence factor is being evaluated, all other factors are to be held relatively 

constant, at a value close to normal. After each test, the taximeter shall be subjected to the recovery 

condition as specified in A.3.3. The operational status of the taximeter shall be recorded for each test. 

When a taximeter is connected in other than a normal configuration, the procedure shall be mutually 

agreed on by the metrological authority and the applicant. 

The tests in Annex A are conducted at the rated operating voltage of 12 V DC unless otherwise 

specified. 

A.5.2 Interfaces (4.2.3) 

Susceptibility that would result from the use of interfaces to other equipment shall be determined in 

the tests. 

A.5.3 Documentation 

Simulators shall be defined in terms of hardware and functionality by reference to the EUT, and by 

any other documentation necessary to ensure reproducible test conditions. This information shall be 

attached to, or traceable from, the test report. 
OIML R 21: 2007 (E) 

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A.5.4 Influence factor and disturbance tests (3.5, 5.1.1) 

Table 5- Summary of tests 

Test Characteristic 

under test Criterion § 

Static temperatures (dry heat and cold) influence MPE A.5.4.1 

Damp heat (condensing) disturbance sf A.5.4.2 

Supply voltage variations influence MPE A.5.4.3 

Vibration (random or sinusoidal) influence MPE A.5.4.4 

Immunity to electromagnetic fields disturbance MPE A.5.4.5 

Electrostatic discharge disturbance MPE A.5.4.6 

Electrical transient conduction on voltage supply 

lines or via lines other than supply lines disturbance MPE A.5.4.7 

Note: MPE = maximum permissible error (3.2.1), sf = significant fault (2.4.5.6) 

A.5.4.1 Static temperatures (Dry heat and cold) (3.5.1) 

Static temperature tests are carried out according to basic standard IEC 60068-2-1 [7], IEC 60068-2-2 

[8], IEC 60068-3-1 [9], and according to Table 6. 

Table 6 - Dry heat (non-condensing) and cold 

Environmental 

phenomenon Test specification Test setup 

16 hours at lower 

limit of temperature 

range (see 3.5.1) 

16 hours at upper 

limit of temperature 

range (see 3.5.1) 

Static 

temperatures 

(Dry heat and 

cold) 

Minimum 

temperature 

range of 

80 °C Function control at 

low operating 

temperature 

Function control at 

high operating 

temperature 

IEC 60068-2-2 

IEC 60068-2-1 

IEC 60068-3-1 

Note: Use IEC 60068-3-1 for background information. 
OIML R 21: 2007 (E) 

40 

Supplementary information to the IEC test procedures: 

Object of the test: To verify compliance with the provisions in 5.1.1 under conditions of dry 

heat (non-condensing) and cold tests conducted separately. 

Pre-condition: None required. 

Condition of the EUT: Supply voltage (12 V DC) is on for 16 hours at upper temperature limit, 

and off for 16 hours at the lower temperature limit, with the exception that 

voltage shall be switched on during the function control test (A.4.4) at the 

low operating temperature. There shall be sufficient temperature 

stabilization after each test. 

Test sequence: The test consists of exposure of the EUT to the upper and lower limits 

of the specified temperature range for 16 hours each. At the end of each 

temperature test, function control shall then be conducted at each 

specified operating temperature after sufficient temperature stabilization 

has occurred. 

(a) The EUT is exposed to the high temperature range limit for 16 

hours, with the voltage on. At the end of the 16 hours after 

sufficient temperature stabilization the function control test (A.4.4) 

shall then be conducted at the specified high operating temperature, 

with the voltage supply on; 

(b) The EUT is exposed to the low temperature range limit for 16 

hours, with the voltage off. At the end of the 16 hours after 

sufficient temperature stabilization the function control test (A.4.4) 

shall then be conducted at the specified low operating temperature, 

with the voltage supply switched on. 

Number of test cycles: At least one cycle. 

Test information: After sufficient temperature stabilization record the following: 

(a) date and time; 

(b) temperature; 

(c) relative humidity; 

(d) supply voltage; 

(e) pulse voltage levels; 

(f) frequency levels; 

(g) errors; 

(h) functional performance; 

(i) indications (as applicable). 

The change of temperature shall not exceed 1 °C/min during heating and 

cooling. 

Maximum allowable 

variations: 

All functions shall operate as designed. 

All errors shall be within the maximum permissible errors specified in 

3.2.1 for initial verification. 

Note: Repeat the function control test at ambient environmental conditions 

after completion of the static temperatures test. Check the recorded 

information. 
OIML R 21: 2007 (E) 

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A.5.4.2 Damp heat cyclic (condensing) test (5.1.2) 

Damp heat, cyclic tests are carried out according to basic standard IEC 60068-3-4 [10], IEC 60068-2-30 

[11], and according to Table 7. 

Table 7 - Damp heat cyclic test 

Environmental 

phenomenon Test specification Test setup 

Damp heat, cyclic 24 hour cycle temperature variations between + 25 °C 

and + 55 °C, maintaining the relative humidity above 

95 % during the temperature change and low 

temperature phases (the first 12 hours), and at 93 % at 

the upper temperature phases (next 12 hours).

IEC 60068-2-30 

IEC 60068-3-4 

Supplementary information to the IEC test procedures: 

Object of the test: To verify compliance with the provisions in 5.1.2 after conditions of high 

humidity and cyclic temperature changes. 

Pre-condition: 

Pre-condition: After a visual inspection and functional test, the EUT shall 

be introduced in the humidity chamber in an unpacked, switched off, 

ready-for-use state and left at 25 °C, 65% R.H. for at least 1 hour before 

starting the first cycle. 

Condition of the EUT: Supply voltage (12 V DC) is switched off for the duration of the test. 

The handling of the EUT shall be such that condensation should occur on 

the EUT during the temperature rise. All parts of the EUT are within 3 °C 

of their final temperature. 

Test sequence: 24 hour cycle sequence: 

(a) First 3 hours – temperature rise from the specified low; 

(b) Temperature maintained at the specified high until 12 hours from start 

of the cycle; 

(c) Temperature lowered from the specified high to the specified low 

within the next 3-6 hours; 

(d) Temperature maintained at the specified low until the 24-hour cycle 

is completed. 

Number of test cycles: At least two cycles. 

Test information: After sufficient temperature stabilization record the following: 

(a) date and time; 

(b) temperature; 

(c) relative humidity; 

(d) supply voltage; 

(e) pulse voltage levels; 

(f) frequency levels; 

(g) errors; 

(h) functional performance; 

(i) indications (as applicable). 

Maximum allowable 

variations: 

After the disturbance, no significant fault shall occur. 
OIML R 21: 2007 (E) 

42 

Note: Conduct the function control test (A.4.4) at ambient environmental 

conditions after completion of the damp heat cyclic tests. Check the 

recorded information. 

A.5.4.3 Supply voltage variations (3.5.2) 

A.5.4.3.1 DC voltage supply test 

Supply voltage limit variations tests are carried out according to ISO 16750-2 [12], and in accordance 

with Table 8. 

Table 8 – Supply voltage variations 

Environmental 

phenomenon Test specification Test setup 

DC voltage 

variations Unom = 12 V Umax =16 V Umin = 9 V ISO 16750-2 

Notes: 

(1) For a 12 V battery, the nominal voltage (Unom) of the electrical system in road 

vehicles is usually 12 V DC, but the voltage at the battery-terminal points can vary 

considerably. 

(2) For other battery voltage systems, the appropriate corresponding voltages shall be 

applied. 

Supplementary information to the ISO test procedures:

Object of the test: To verify compliance with the provisions in 5.1.1 of voltage variations at 

the lower and upper limits of the voltage range. 

Preconditioning: None. 

Condition of the EUT: Supply voltage (12 V DC) is switched on for the duration of the test. 

Test sequence: The test consists of exposure to the specified battery condition for a 

period sufficient for achieving temperature stability and for performing 

the required measurements. 

Number of test cycles: At least one cycle. 

Test information: After stabilization of the EUT at the nominal voltage and at ambient 

conditions conduct the function test in A.4.3 at the upper (16 V DC) and 

lower (9 V DC) limits and record: 

(a) date and time; 

(b) temperature; 

(c) relative humidity; 

(d) supply voltage; 

(e) pulse voltage levels; 

(f) frequency levels; 

(g) errors; 

(h) functional performance; 

(i) indications (as applicable). 

Maximum allowable 

variations: 

All functions shall operate as designed. 

All errors shall be within the maximum permissible errors specified in 

3.2.1 for initial verification. 
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A.5.4.3.2 Voltage drop below lower operating voltage limit (5.2.5) 

There is no reference to standards for this test. Refer to Table 9 for the test conditions. 

Table 9 – Voltage reductions below lower operating limit 

Environmental 

phenomenon Test specification Test setup 

% of lower 

value of 

voltage 

reduction, VL

Width of 

reduction 

(seconds) 

Requirement 

7, 14 Taximeter should show the 

previously indicated fare 

15, 17.5 20 Taximeter should show the 

previously indicated fare or 

switch to the “For Hire” 

(Free) operating position 

Slow dips 

below the 

lower 

operating 

voltage limit 

90, 40, 0 

21, 30 Taximeter should switch to 

the “For Hire” operating 

position 

No reference to 

standards at 

present 

Note: For specifications of the supply voltage used during the test to simulate the battery, 

refer to ISO 7637-2 [20], clause 4.4 [8]. 
OIML R 21: 2007 (E) 

44 

Supplementary information: 

Object of the test: To verify compliance with the provisions in 5.1.1 under conditions of 

slow battery voltage dips. 

Pre-condition: None.

Condition of the EUT: Before any test stabilize the EUT under constant environmental 

conditions. 

Test sequence: The test consists of exposure of the supply voltage to the specified 

conditions in Table 9, observing the behavior of the taximeter. 

Manually apply slow voltage reductions below the lower voltage limit 

for the varying amounts of time listed in Table 9. 

Additionally, reverse (incorrect) polarity shall be applied for 30 

seconds. This shall cause no detectable change in registered 

information. 

If a standard supply voltage (with sufficient current capacity) is used 

in bench testing to simulate the battery, the low internal impedance of 

the battery shall also be simulated. 

The continuous supply source shall have an internal resistance Ri less 

than 0.01 Ω and an internal impedance Zi = Ri for frequencies less than 

400 Hz. 

Test information: The function control test in A.4.4 shall run during the application of 

the dips. Record: 

(a) date and time; 

(b) temperature; 

(c) relative humidity; 

(d) supply voltage; 

(e) indications (as applicable); 

(f) errors; 

(g) functional performance. 

Maximum allowable 

variations: All functions shall operate as designed. 

All errors shall be within the maximum permissible errors specified in 

3.2.1 for initial verification. 

Notes: Repeat the function control test (A.4.4) at ambient environmental 

conditions after completion of the voltage variations test. Check the 

recorded information. 
OIML R 21: 2007 (E) 

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A.5.4.4 Vibration (random or sinusoidal) 

Two different vibration tests (random or sinusoidal) are described below. In general, the random 

vibration test is recommended. The sinusoidal vibration test may be applied if specified by national 

regulations. Guidance for the selection amongst both the tests can be found in IEC 60068-3-8 [13].

A.5.4.4.1 Vibration (random) 

Vibration (random) tests are carried out according to basic standard IEC 60068-2-64 [14], 

 IEC 60068-2-47 [15], IEC 60068-3-8 [13], and according to Table 10. 

Table 10 - Vibration (random) test 

Environmental 

phenomenon Test specification Test setup 

Frequency range: 10 Hz to 150 Hz 

Total RMS level: 7 ms–2

ASD level 10 Hz – 20 Hz: 1 m2s

–3

ASD level 20 Hz – 150 Hz: – 3 dB/octave 

Number of axes: 3 

Random 

vibrations 

Duration per axis: At least 30 minutes 

IEC 60068-2-64 

IEC 60068-2-47 

IEC 60068-3-8 
OIML R 21: 2007 (E) 

46 

Supplementary information to the IEC test procedures: 

Object of the test: To verify that the EUT complies with the provisions in 5.1.1 under 

conditions of random vibrations. 

Pre-condition: None required. 

Condition of the EUT: Supply voltage is switched on for the duration of the test. 

Mount the EUT on a rigid fixture by its normal mounting means, such 

that the gravitational force acts in the same direction as it would in 

normal use. Where the effect of gravitational force is not important, the 

EUT may be mounted in any position. 

Test sequence: In accordance with the specifications in Table 10, apply random vibrations, 

over the specified frequency range, to the EUT, in three mutually 

perpendicular axes (2 horizontal and 1 vertical) in turn, for 30 minutes per 

axis. 

Number of test cycles: At least one cycle. 

Test information: Conduct the function control test (A.4.3) and record: 

(a) date and time; 

(b) temperature; 

(c) supply voltage; 

(d) frequency range; 

(e) total RMS; 

(f) ASD levels; 

(g) number of axes and duration per axis; 

(h) pulse levels; 

(i) frequency levels; 

(j) errors; 

(k) functional performance; 

(l) indications (as applicable). 

Maximum allowable 

variations: 

All functions shall operate as designed. 

All errors shall be within the maximum permissible errors specified in 

3.2.1 for initial verification. 

Note: Repeat the function control test at ambient environmental conditions 

after completion of the random vibrations test. Check the recorded 

information. 
OIML R 21: 2007 (E) 

47 

A.5.4.4.2 Vibration (sinusoidal) 

Vibration (sinusoidal) tests are carried out according to basic standard IEC 60068-2-6 [16], 

IEC 60068-2-47 [15], IEC 60068-3-8 [13], and according to Table 11. 

Table 11 - Vibration (sinusoidal) test 

Environmental 

phenomenon Test specification Test setup 

Frequency range: 10 Hz to 150 Hz 

Max acceleration level: 10 ms–2

Number of axes: 3 

Sinusoidal vibrations 

Number of sweeps per axis: 20 

IEC 60068-2-6 

IEC 60068-2-47 

IEC 60068-3-8 
OIML R 21: 2007 (E) 

48 

Supplementary information to the IEC test procedures: 

Object of the test: To verify that the EUT complies with the provisions in 5.1.1 under 

conditions of sinusoidal vibrations. 

Pre-condition: None required. 

Condition of the EUT: Normal voltage is switched on for the duration of the test. 

Mount the EUT on a rigid fixture by its normal mounting means, such 

that the gravitational force acts in the same direction as it would in 

normal use. Where the effect of gravitational force is not important, the 

EUT may be mounted in any position. 

Test sequence: In accordance with the specifications in Table 11, apply sinusoidal 

vibrations, over the specified frequency range, at 1 octave/min, at the 

specified acceleration level with a specified number of sweep per axis, in 

three mutually perpendicular main axes (2 horizontal and 1 vertical) of the 

rigidly mounted EUT. 

Number of test cycles: At least one cycle. 

Test information: Conduct the function control test (A.4.3) and record: 

(a) date and time; 

(b) temperature; 

(c) frequency range; 

(d) acceleration level; 

(e) sweep per axis; 

(f) number of axes and duration per axis; 

(g) pulse levels; 

(h) frequency levels; 

(i) errors; 

(j) functional performance; 

(k) indications (as applicable). 

Maximum allowable 

variations: All functions shall operate as designed. 

All errors shall be within the maximum permissible errors specified in 

3.2.1 for initial verification. 

Note: 

Repeat the function control test at ambient environmental conditions 

after completion of the sinusoidal vibration test. Check the recorded 

information. 
OIML R 21: 2007 (E) 

49 

A.5.4.5 Immunity to electromagnetic fields 

A.5.4.5.1 Immunity to radiated electromagnetic fields 

Radiated, radio frequency, electromagnetic field immunity tests are carried out in accordance with 

IEC 61000-4-3 [17], and according to Table 12. 

The unmodulated carrier of the test signal is adjusted to the indicated test value. To perform the test 

the carrier is in addition modulated as specified. 

Table 12 - Radiated electromagnetic field 

Test specification 

Environmental 

phenomenon 

Frequency ranges 

(MHz) 

Field strength 

(V/m) 

Test setup 

80 to 2000(1)

Radiated 

electromagnetic field 26 to 80(2)

24(3) IEC 61000-4-3 

Modulation 80 % AM, 1 kHz sine wave 

 Notes: 

(1) IEC 61000-4-3 only specifies test levels above 80 MHz. For 

frequencies in the lower range the test methods for conducted radio 

frequency disturbances are recommended (A.5.4.2.2); 

(2) For EUT having no I/O ports available so that the test according to 

A.5.4.5.2 cannot be applied, the lower limit of the radiation test is 

26 MHz; 

(3) 24 V/m is the recommended severity level concerning electronic sub 

assemblies installed in motor vehicles [see the Automotive EMC 

Directive (2004/104/EC)]. However, in accordance with national 

regulations a severity level of 10 V/m may be applied. 
OIML R 21: 2007 (E) 

50 

Supplementary information to the IEC test procedures: 

Object of the test: To verify compliance with the provisions in 5.1.3 under conditions of 

specified electromagnetic fields applied to the taximeter. 

Pre-condition: None required. 

Condition of the EUT: Before any test stabilize the EUT under constant environmental conditions. 

The electromagnetic field can be generated in different facilities, the use 

of which is limited by the dimensions of the EUT and the frequency 

range of the facility. 

Test sequence: The EUT shall be exposed to electromagnetic field strength as specified 

in Table 12. 

When using an electronic pulse generator to simulate the pulses 

produced by a typical distance measurement transducer, care should also 

be taken not to let the pulse generator be affected by the electromagnetic 

waves by using a suitable method of electromagnetic isolation. 

Alternatively a mechanically driven pulse generator may be used. 

Test information: Record: 

(a) date and time; 

(b) temperature; 

(c) supply voltage; 

(d) test setup information; 

(e) supply voltage; 

(f) indications (as applicable); 

(g) errors; 

(h) functional performance. 

Maximum allowable 

variations: All errors shall be within the maximum permissible errors specified in 

3.2.1 for initial verification. 
OIML R 21: 2007 (E) 

51 

A.5.4.5.2 Immunity to conducted radio-frequency, electromagnetic fields 

Conducted electromagnetic field immunity tests (radio-frequency electromagnetic fields lower than 

80 MHz) are carried out in accordance with IEC 61000-4-6 [18], and according to Table 13. 

Table 13 - Immunity to conducted radio-frequency, electromagnetic 

Test specification 

Environmental 

phenomenon 

Frequency range 

(MHz) 

RF amplitude (50 Ω) 

(V e.m.f) Test setup 

Conducted 

electromagnetic field 

0.15 to 80 24(2) V IEC 61000-4-6 

Modulation 80 % AM, 1 kHz sine wave 

Notes: 

(1) This test shall only be performed when the cable length connected to 

the taximeter exceeds 3 m; 

(2) 24 V is the recommended severity level concerning electronic sub 

assemblies installed in motor vehicles (see the Automotive EMC 

Directive (2004/104/EC)). However, in accordance with national 

regulations a severity level of 10 V may be applied. 

Supplementary information to the IEC test procedures: 

Object of the test: To verify compliance with the provisions in 5.1.3 under conditions of 

specified conducted electromagnetic fields. 

Pre-condition: The performance of the test equipment, consisting of an RF generator, 

RF amplifiers, (de-)coupling devices, attenuators, etc., shall be verified 

before testing commences. 

Condition of the EUT: Before any test, stabilize the EUT under constant environmental 

conditions. 

Test sequence: The EUT shall be exposed to electromagnetic field strength as 

specified in Table 13. 

Radio frequency electromagnetic current, simulating the influence of 

electromagnetic fields on conductors, shall be coupled or injected into 

EUT ports for voltage, inputs, and outputs using coupling/decoupling 

devices as defined in the referred standard. 

Test information: Record: 

(a) date and time; 

(b) temperature; 

(c) test setup information; 

(d) supply voltage; 

(e) indications (as applicable); 

(f) errors; 

(g) functional performance. 

Maximum allowable 

variations: 

All errors shall be within the maximum permissible errors specified in 

3.2.1 for initial verification. 
OIML R 21: 2007 (E) 

52 

A.5.4.6 Electrostatic discharge tests 

Electrostatic discharge tests are carried out in accordance with IEC 61000-4-2 [19], and according to 

Table 14. 

Table 14 - Electrostatic discharge tests 

Environmental 

phenomenon Test specification Test setup 

Test voltage Levels 

contact discharge 6 kV(1) (2)

Electrostatic 

discharge 

air discharge 8 kV(1)

IEC 61000-4-2 

Notes: 

(1) Tests shall also be performed at the specified lower voltage levels in 

the IEC 61000-4-2 standard up to and including the levels specified 

above; 

(2) 6 kV is the recommended maximum contact discharge level and shall 

be applied to conductive accessible parts. Metallic contacts, e.g. in 

battery compartments or in socket outlets are excluded from this 

requirement. However, in accordance with national regulations a lower 

maximum contact discharge level of 4 kV may be applied. 
OIML R 21: 2007 (E) 

53 

Supplementary information to the IEC test procedures: 

Object of the test: To verify compliance with the provisions in 5.1.3 under conditions 

where direct and indirect electrostatic discharges are applied. 

Pre-condition: Before starting the tests, the performance of the electrostatic discharge 

generator as defined in IEC 61000-4-2 shall be verified. 

Condition of the EUT: Before any test stabilize the EUT under constant environmental 

conditions. 

Test sequence: The EUT shall be exposed to electrostatic discharge tests as specified 

in Table 14. 

The taximeter and any relevant devices shall be operational during this 

test. 

At least 10 discharges shall be applied. The time interval between 

successive discharges shall be at least 10 seconds. For EUT not 

equipped with a ground terminal, the EUT shall be fully discharged 

between discharges. 

Contact discharge is the preferred test method. Air discharge shall be 

used were contact discharge cannot be applied. 

Direct application: 

In the contact discharge mode to be carried out on conductive surfaces, 

the electrode shall be in contact with the EUT. 

In the air discharge mode on insulated surfaces, the electrode is 

approached to the EUT and the discharge occurs by spark. 

Indirect application: 

The discharges are applied in the contact mode to coupling planes 

mounted near the EUT. 

Test information: Record: 

(a) date and time; 

(b) temperature; 

(c) test setup information; 

(d) supply voltage; 

(e) indications (as applicable); 

(f) errors; 

(g) functional performance. 

Maximum allowable 

variations: 

All errors shall be within the maximum permissible errors specified in 

3.2.1 for initial verification. 

Note: Repeat the function control test at ambient environmental conditions 

after completion of the electrostatic discharge test. Check the recorded 

information. 
OIML R 21: 2007 (E) 

54 

A.5.4.7 Electrical transient conduction 

A.5.4.7.1 Conduction along supply lines of external 12 V road vehicle battery 

For this test refer to ISO 7637-2 [20], and to Table 15. 

Table 15 - Electrical transient conduction on 12 V supply lines 

Environmental 

phenomenon Test specification Test setup 

Pulse voltage, Us

Test pulse 

Unom = 12 V 

1 – 100 V 

2a + 50 V 

2b + 10 V 

3a – 150 V 

3b + 100 V 

Electrical transient 

conduction on supply 

lines 

4 – 7 V 

ISO 7637-2 

Notes: 

(1) Test pulse 2b is only applicable if the instrument is connected 

to the battery via the main (ignition) switch of the car, i.e. if 

the manufacturer has not specified that the instrument is to be 

connected directly (or by its own main switch) to the battery; 

(2) No reference has been made to test pulses 5a and 5b. 
OIML R 21: 2007 (E) 

55 

Supplementary information to the ISO test procedures: 

Applicable standards: ISO 7637-2 

§ 5.6.1: Test pulse 1 

§ 5.6.2: Test pulse 2a + b 

§ 5.6.3: Test pulse 3a + 3b 

§ 5.6.4: Test pulse 4 

Object of the test: To verify compliance with the provisions in 5.1.3 under the following 

conditions: 

 transients on the supply lines due to supply disconnection 

from inductive loads (pulse 1); 

 transients due to a sudden interruption of currents in a device 

connected in parallel with the device under test due to the 

inductance of the wiring harness (pulse 2a); 

 transients from DC motors acting as generators after the 

ignition is switched off (pulse 2b); 

 transients on the supply lines, which occur as a result of the 

switching processes (pulses 3a and 3b); 

 voltage reductions caused by energizing the starter-motor 

circuits of internal combustion engines (pulse 4). 

Preconditioning: None 

Condition of the EUT: Before any test, stabilize the EUT under constant environmental 

conditions. 

Test sequence: The test consists of exposure to conducted disturbances on the supply 

voltage by direct brief coupling onto supply lines of the strength and 

character as specified in Table 15 while the taximeter is switched on.

Test information: Record: 

(a) date and time; 

(b) temperature; 

(c) test setup information; 

(d) supply voltage; 

(e) indications (as applicable); 

(f) errors; 

(g) functional performance. 

Maximum allowable 

variations: 

No significant error during the disturbance, except for test 2b. For test 

2b, no significant error after the disturbance. 
OIML R 21: 2007 (E) 

56 

A.5.4.7.2 Electrical transient conduction via lines other than supply lines 

of 12 V road vehicle battery 

Electrical conduction by capacitive and inductive coupling on signal lines is carried out in accordance 

with ISO 7637-3 [21], and according to Table 16. 

Table 16 – Electrical transient conduction via lines other than supply lines 

Environmental phenomenon Test specification Test setup 

Pulse voltage, Us

Test pulse 

Unom = 12 V 

a – 60 V 

Electrical transient 

conduction via lines other 

than supply lines 

b + 40 V 

ISO 7637-3 

Supplementary information to the ISO test procedures: 

Object of the test: To verify compliance with the provisions in 5.1.3 under conditions 

of transients which occur via lines other than supply lines because 

of the switching processes (pulses a, and b). 

Preconditioning: None. 

Condition of the EUT: Before any test stabilize the EUT under constant environmental 

conditions. 

Test sequence: The test consists of exposure of the EUT to conducted 

disturbances (bursts of voltage spikes by capacitive and inductive 

coupling on signal lines) of the strength and character as specified 

in Table 16 while the taximeter is switched on. 

Test information: Apply the test pulses and record the following: 

(a) date and time; 

(b) temperature; 

(c) test setup information; 

(d) supply voltage; 

(e) indications (as applicable); 

(f) errors; 

(g) functional performance. 

Repeat the test for the defined pulses and record the indications. 

Maximum allowable 

variations: No significant error during the disturbance. 

Note: Repeat the function control test at ambient conditions after 

completion of the transient conduction via supply lines test. Check 

the recorded information. 
OIML R 21: 2007 (E) 

57 

Annex B 

(Informative) 

General information on the conditions for the compatibility between a 

taximeter and a distance measurement transducer 

B Compatibility for use with distance measurement generator 

The conditions for the compatibility between the taximeter and the distance measurement generator 

shall be specified by the manufacturer of the taximeter and checked in accordance with the appropriate 

parts of OIML R 21. 

B.1 Description and purpose 

The distance measurement transducer is installed in the taxi and its purpose is to provide a taximeter 

with secured distance information representative of the distance traveled by the taxi. The transducer is 

interfaced to a moving part of the taxi and it may be located in any part of the taxi. In its operational 

mode, the distance measurement transducer is connected to a taximeter. There are two principles of 

operation: 

(a) An analog transducer sends electrical impulses with a frequency proportional to the velocity to the 

taximeter. 

(b) A software controlled transducer calculates the velocity and transmits the value of the quantity in a 

datagram via a fieldbus to the taximeter. 

A typical distance measurement transducer is described in Figure A. 

B.2 Suitability and security of operation 

The design of the distance measurement transducer shall suit the method of operation and vehicle for 

which it is intended. The distance measurement transducer shall be capable of providing the following 

functions: 

 give a stable signal at every speed traveled; 

 have defined characteristics regarding voltage level, pulse width and the relation of speed and 

frequency; 

Processing unit 

Security devices 

DC Power 

Distance 

information 

Connector 

Distance 

data 

Taximeter 

Interface to vehicle 

Figure A - Typical distance measurement transducer 
OIML R 21: 2007 (E) 

58 

 be able to establish and authenticate, for any interaction, the identity of any device that it is 

connected to, at connection and at power supply recovery; 

 ensure that motion information may only be processed and derived from the transducer 

interface; 

 exchange distance information with associated security attributes to ensure integrity and 

authenticity of measurement data; 

 any change in the instrument characteristics or software shall only be possible by breaking 

seals. 

The distance measuring transducer may incorporate capabilities for the secure processing, 

transmission and storage of information pertaining to the transducer identification and connected 

device identity. 

B.3 Metrological characteristics of the transducer 

The documentation provided by the manufacturer of the distance measurement transducer shall 

include the following: 

 name and address of the manufacturer; 

 approval of the transducer and/or interconnected devices if applicable; 

 technical specifications; 

 metrological characteristics of the transducer; 

 functional description of the transducer; 

 description of securing; 

 software information (if applicable); 

 drawings, diagrams and general information explaining the construction and operation; 

 any document or other evidence that the design and construction of the transducer conforms to 

appropriate international standards. 
OIML R 21: 2007 (E) 

59 

Annex C 

(Mandatory) 

Test report format 

Explanatory notes on the Test report format 

This "Test report format" aims at presenting, in a standardized format, the results of the various tests and 

examinations to which a type of a taximeter shall be submitted with a view to its approval. 

The Test report format consists of two parts, a "checklist" and the "test report" itself: 

 The checklist is a summary of the examinations carried out on the instrument. It includes the 

conclusions of the results of the test performed, experimental or visual checks based on the 

requirements of R 21. 

 The test report is a record of the results of the tests carried out on the instrument. The "test 

report" forms have been produced based on the tests detailed in Annex A of this International 

Recommendation. 

It is recommended that all metrology services or laboratories evaluating types of taximeter according to 

R 21 or to national or regional regulations based on this OIML Recommendation use this Test report 

format, directly or after translation into a language other than English. 

It is also recommended that this Test report format be transmitted by the country performing these tests 

to the relevant authorities of another country, under bi- or multilateral cooperation agreements. 

In the framework of the OIML Certificate System for measuring instruments, use of this Test report 

format is mandatory. 

The "information concerning the test equipment used for type evaluation" shall cover all test equipment 

which has been used in determining the test results given in a report. The information may be a short list 

containing only essential data (name, type, reference number for the purpose of traceability). For 

example: 

 Verification standards (accuracy, or accuracy class, and number); 

 Simulator for testing of devices (name, type, traceability and number); 

 Climatic test and static temperature chamber (name, type and number); 

 Electrical tests, bursts (name of the instrument, type and number); 

 Description of the procedure of field calibration for the test of immunity to radiated 

electromagnetic fields. 

Note concerning the numbering of the following pages 

A special place is left at the top of each page (starting with the following page) for numbering the pages 

of reports established following this model. In particular, some tests (e.g. metrological performance tests) 

shall be repeated several times, each test being reported individually on a separate page following the 

relevant format. 

For a given report, it is advisable to complete the sequential numbering of each page by the indication of 

the total number of pages of the report. 
OIML R 21: 2007 (E) Report page .....of ..... 

60 

TAXIMETER 

TYPE EVALUATION REPORT 

EXPLANATORY NOTES 

Symbols, units and abbreviations: 

I Indication 

Res. Resolution 

MPE Maximum permissible error 

EUT Equipment Under Test 

sf Significant fault 

k Number of pulses per kilometre traveled received by a taximeter 

Temp Temperature 

Ref. Reference (values) 

Unom Nominal voltage value marked on the instrument 

Umax Highest value of a voltage range marked on the instrument 

Umin Lowest value of a voltage range marked on the instrument 

e.m.f Electromotive force 

I/O Input / Output ports 

RF Radio frequency 

V/m Volts per metre 

kV Kilovolt 

DC Direct current 

Hz Hertz, cycles per second (unit of frequency measurement) 

MHz Megahertz 

ms–2 Metres per second per second 

Pulses/km Pulses per kilometre 

ASD Acceleration spectral density 

RMS Root-mean-square acceleration 

The name(s) or symbol(s) of the unit(s) used to express test results shall be specified in each test form. 

For each test, the "SUMMARY OF TYPE EVALUATION" and the 

"CHECKLIST" shall be completed according to this example: P F 

P = Passed 

F = Failed 

when the instrument has passed the test: X 

when the instrument has failed the test: X 

when the test is not applicable: ⎯ ⎯

The blank spaces in boxes in the headings of the report should always be filled in according to the 

following example: 
OIML R 21: 2007 (E) Report page .....of ..... 

61 

At start At end 

Temp: 20.5 21.1 °C 

Rel. h.: % 

Date: 2006-01-29 2006-01-30 yyyy-mm-dd 

Time: 16:00:05 16:30:25 hh:mm:ss 

"Date" in the test report(s) refers to the date on which the test was performed. 

In the disturbance tests, faults greater than the value specified in 2.4.5.6 are acceptable provided that 

they are detected and acted upon, or that they result from circumstances such that these faults shall not 

be considered as significant; an appropriate explanation shall be given in the column "Yes (remarks)". 

Section numbers in brackets refer to the corresponding subclauses of R 21. 
OIML R 21: 2007 (E) Report page .....of ..... 

62 

GENERAL INFORMATION CONCERNING THE TYPE 

Application no.:................................................ Manufacturer’s name and address:......................... 

Applicant:........................................................ Date instrument submitted:.................................... 

Type designation:.............................................. Evaluation period: Start:.......... End:............ 

Report date:..................................................... Observer:......................................................... 

Issuing Institute name and address:...................................................................................................... 

Taximeter Testing on: 

Device1

Characteristic values: 

Time tariff 

(I/h) 

Distance tariff 

(I/km) 

Taximeter constant, k

(pulses/km) 

Measuring range 

Fare 

increment 

step 

(I) 

Min Max Res. Min Max Res. Min Max Res. Distance 

(km) 

Time 

(h) 

Battery voltage2: 12 V Other battery power supply: ............................................. 

Unom = V Umin = V Umax = V 

Printer: Built-in Connected Not present but connectable No connection 

Temperature range: °C Min: °C Max: °C 

Software identification of the type: 

 

1

 The test equipment connected to the taximeter shall be defined in the test form(s) used. 

2

 The rated operating voltage is 12 V DC. For other voltage systems, e.g. 24 V DC, the appropriate corresponding voltages shall be applied 

for the tests. 
OIML R 21: 2007 (E) Report page .....of ..... 

63 

Additional remarks: 

Use this space to indicate additional remarks and/or information: other connected devices and interfaces, choice of the 

manufacturer regarding protection against disturbances, etc.
OIML R 21: 2007 (E) Report page .....of ..... 

64 

IDENTIFICATION OF THE INSTRUMENT

Application no.: ..................................................................................... 

Report date: ..................................................................................... 

Type designation: ..................................................................................... 

Manufacturer: ...................................................................................... 

Serial no.: ...................................................................................... 

Manufacturing documentation: 

(Record as necessary to identify the equipment under test) 

System or device 

name 

Drawing number or software 

identification 

Issue or reference level Serial or reference no. 

..................... ........................................ ........................................ ........................................ 

..................... ........................................ ........................................ ........................................ 

..................... ........................................ ........................................ ........................................ 

..................... ........................................ ........................................ ........................................ 

..................... ........................................ ........................................ ........................................ 

..................... ........................................ ........................................ ........................................ 

..................... ........................................ ........................................ ........................................ 

..................... ........................................ ........................................ ........................................ 

..................... ........................................ ........................................ ........................................ 

..................... ........................................ ........................................ ........................................ 

..................... ........................................ ........................................ ........................................ 

..................... ........................................ ........................................ ........................................ 

..................... ........................................ ........................................ ........................................ 

..................... ........................................ ........................................ ........................................ 

..................... ........................................ ........................................ ........................................ 

..................... ........................................ ........................................ ........................................ 

..................... ........................................ ........................................ ........................................ 
OIML R 21: 2007 (E) Report page .....of ..... 

65 

Description or other information pertaining to identification of the instrument: 

(attach photograph here if available) 
OIML R 21: 2007 (E) Report page .....of ..... 

66 

INFORMATION CONCERNING THE TEST EQUIPMENT3 USED FOR 

TYPE EVALUATION 

TEST EQUIPMENT 

Application no.: ..................................................................................... 

Report date: ..................................................................................... 

Type designation: ..................................................................................... 

Manufacturer: ...................................................................................... 

List all test equipment used in this report: 

Equipment 

name or 

description 

Manufacturer Type or 

reference no. 

Serial or 

identification 

no. 

Calibration 

date 

Measurement 

uncertainty 

(if applicable) 

Used for 

(test 

references) 

Power supply .................. .................. .................. .................. .................. .................. 

Pulse counter .................. .................. .................. .................. .................. .................. 

Timer .................. .................. .................. .................. .................. .................. 

Electrostatic 

discharge 

generator .................. .................. .................. .................. .................. .................. 

Pulse generator .................. .................. .................. .................. .................. .................. 

EMC chamber .................. .................. .................. .................. .................. .................. 

Climatic 

chamber .................. .................. .................. .................. .................. .................. 

.................. .................. .................. .................. .................. .................. 

.................. .................. .................. .................. .................. .................. 

.................. .................. .................. .................. .................. .................. 

.................. .................. .................. .................. .................. .................. 

.................. .................. .................. .................. .................. .................. 

.................. .................. .................. .................. .................. .................. 

.................. .................. .................. .................. .................. .................. 

.................. .................. .................. .................. .................. .................. 

 

3

 For traceability, test equipment with traceable calibration to national and international standards shall be used to perform the measurements. 
OIML R 21: 2007 (E) Report page .....of ..... 

67 

CONFIGURATION FOR TEST 

Provide additional information relating to equipment configuration, interfaces, data rates, EMC protection 

options, etc., for the instrument and/or simulator. 

Test connector: 

– Input signals: Output signals: 

Distance pulses: Distance pulses: 

Low-high: Low-high: 

High-low: High-low: 

Max. freq. (Hz): 

Time pulses: Time pulses: 

Low-high: Low-high: 

High-low: High-low: 

Min. freq. (Hz): Internal clock freq. (Hz): 

Max. freq. (Hz): Signal to indicate fare increment: 

Signal to block time-counting when: Low-high signal: 

Signal is low: High-low signal: 

Signal is high: 

Distance sensor interface: 

Low voltage: 

High voltage: 

Trigger: 

Low-high: 

Use this space for additional information relating to equipment configuration. 
OIML R 21: 2007 (E) Report page .....of ..... 

68 

SUMMARY OF TYPE TEST REPORT 

Application no.: ..................................................................................... 

Report date: ..................................................................................... 

Type designation: ..................................................................................... 

Test 

category 

Annex 

C Test Test reference 

Report 

page 

Passed Failed Remarks 

1 C.1 Initial examination and function 

test A.4.3 

C.2.1 Static temperatures - Dry heat 

and cold function control 

A.5.4.1 

C.2.2 Damp heat cyclic (condensing) 

function control 

A.5.4.2 

2 

C.2.3 Function control test after static 

temperatures and damp heat 

cyclic test 

A.4.4 

C.2.4 Voltage drop below lower limit 

function control 

A.5.4.3 

3 C.2.4.1 Function control after voltage 

variations test A.4.4 

C.2.5 Random vibration function 

control, or A.5.4.4.1 

C.2.5.1 Sinusoidal vibration function 

control A.5.4.4.2 4 

C.2.5.2 Function control after vibrations 

test A.4.4 

C.2.6.1 Immunity to radiated 

electromagnetic fields A.5.4.5.1 

C.2.6.2 Immunity to conducted 

electromagnetic fields A.5.4.5.2 

C.2.6.3 Electrostatic discharge test A.5.4.6 5 

C.2.6.4 Function control after 

electromagnetic fields and 

electrostatic discharge tests 

A.4.4 

C.2.7.1 Electrical transient conduction 

along supply lines A.5.4.7.1 

C.2.7.2 Electrical transient conduction 

via lines other lines than supply 

lines 

A.5.4.7.2 

6 

C.2.7.3 Function control after transient 

conduction tests A.4.4 

Examination of the construction 7 C.3 Checklist 
OIML R 21: 2007 (E) Report page .....of ..... 

69 

C.1 Function test at the beginning of the test program (7.2.1, A.4.3)

At start At end 

Application no.: ...................................................... Temp: °C 

Type designation: ..................................................... Rel. h.: % 

Observer: ..................................................... Date: yyyy-mm-dd 

Time: hh:mm:ss 

C.1.1 Initial examination at reference (ambient) conditions 

C.1.1.1 Voltage supply variations test (3.5.2, A.5.4.3.1) 

Battery voltage (DC): 12 V Other battery power supply 

Unom = V Umin = V Umax = V 

Time measurement 

Time signal 

(Hz) 

Number of test 

pulses 

Indication, I Time signal 

error 

Test pulses 

error 

12 V 

DC 

voltage 

supply4 Actual Ref. Actual Ref. Start End 

Time 

tariff 

(I/h) 

Hz % Pulses % 

MPE 

% 

9 V 

16 V 

Distance measurement 

Number of test 

pulses 

Indication, I Test pulses 

error 

12 V 

DC 

voltage 

supply Actual Ref. Start End 

Taximeter 

constant, k

(pulses/ 

km) 

Distance 

tariff 

(I/km) 

Pulses % 

MPE 

% 

9 V 

16 V 

Passed Failed 

Remarks: 

 

4

 Rated operating voltage is 12 V DC (see A.4.1). For other voltage systems the appropriate corresponding voltages shall be applied. 
OIML R 21: 2007 (E) Report page .....of ..... 

70 

C.1.1.2 Pulse frequency levels5

Distance measurement

Number of test 

pulses 

Indication, I Test pulses 

error 

DC 

voltage 

supply 

Pulse frequency6

(Hz) 

Actual Ref. Start End 

Taximeter 

constant, k

(pulses/ 

km) 

Distance 

tariff 

(I/km) 

Pulses % 

MPE 

% 

Lowest 

12 V Medium 

Highest 

Passed Failed 

Remarks:

C.1 Function test (continued) 

C.1.1.3 Pulse voltage levels7

Distance measurement

Number of test 

pulses 

Indication, I Test pulses 

error 

DC 

voltage 

supply 

Pulse voltage 

(V) 

Actual Ref. Start End 

Taximeter 

constant, k

(pulses/ 

km) 

Distance 

tariff 

(I/km) 

Pulses % 

MPE 

% 

Lowest 

12 V Medium 

Highest 

Passed Failed 

Remarks:

 

5

 By testing different pulse frequencies, time measurement is dispensable. 

6

 At least 10 fare increments at simulated speed of up to 200 km/h (7.2.1, A.4.5.1.2). 

7

 By variation of pulse voltage levels, time measurement is dispensable.
OIML R 21: 2007 (E) Report page .....of ..... 

71 

C.1.1.4 Specified k values8

Distance measurement

Number of test 

pulses 

Indication, I Test pulses 

error 

DC 

voltage 

supply 

Taximeter 

constant, k

(pulses/km) Actual Ref. Start End 

Taximeter 

constant, k

(pulses/ 

km) 

Distance 

tariff 

(I/km) 

Pulses % 

MPE 

% 

Lowest 

12 V Medium 

Highest 

Passed Failed 

Remarks:

 

8

 k values (see 2.6). By variation of k values, time measurement is dispensable. 
OIML R 21: 2007 (E) Report page .....of ..... 

72 

C.1 Function test (continued) 

C.1.1.5 Featured calculation method 

Time measurement

Time signal (Hz) Number of test 

pulses 

Indication, I Time 

tariff 

(I/h) 

Time signal 

error 

Test pulses 

error 

DC 

voltage 

supply 

Calculation 

method 

S or D 

Actual Ref. Actual Ref. Start End Hz % Pulses % 

MPE 

% 

12 V 

Distance measurement

Number of test 

pulses 

Indication, I Test pulses 

error 

DC 

voltage 

supply 

Calculation 

method 

S or D Actual Ref. Start End 

Taximeter 

constant, k

(pulses/ 

km) 

Distance 

tariff 

(I/km) Pulses % 

MPE 

% 

12 V 

Passed Failed 

Remarks:
OIML R 21: 2007 (E) Report page .....of ..... 

73 

C.1.1.6 Programmed tariff (including automatic changes, if applicable) 9

Time measurement

Time 

measuring 

signal (Hz) 

Number of test 

pulses 

Indication, I Time signal 

error 

Test pulses 

error 

MPE 

% 

DC 

voltage 

supply 

Tariffs 

Actual Ref. Actual Ref. Start End 

Time 

tariff 

(I/h) 

Hz % Pulses % 

12 V 

Distance measurement

Number of test 

pulses 

Indication, I Test pulses 

error 

DC 

voltage 

supply 

Tariffs 

Actual Ref. Start End 

Taximeter 

constant, k

(pulses/ 

km) 

Distance 

tariff 

(I/km) 

Pulses % 

MPE 

% 

12 V 

Passed Failed 

Remarks: 

 

9

 Tests shall are performed for a selection of the available programming modes and/or tariffs (including automatic changes, if applicable and 

only testing relevant measurement data). 
OIML R 21: 2007 (E) Report page .....of ..... 

74 

C.2 Function control tests during and/or after exposure to influences and/or disturbances 

(7.2.2, A.4.4) 

Tests are conducted in accordance with the test program in Table 2 and the summary in Table 4. All registered 

information shall be checked. 

At start At end 

Application no.: ...................................................... Temp: °C 

Type designation: ..................................................... Rel. h.: % 

Observer: ..................................................... Date: yyyy-mm-dd 

Time: hh:mm:ss 

C.2.1 Dry heat (non-condensing) and cold tests10 (3.5.1, A.5.4.1) 

Time measurement

Time measuring 

signal (Hz) 

Test pulses Indication, I Time signal 

error 

Test pulses 

error 

DC 

Voltage 

supply 

Operating 

temperature 

Actual Ref. Actual Ref. Start End 

Time 

tariff 

(I/h) 

Hz % Pulses % 

MPE 

% 

Specified 

high 

(dry heat) 12 V 

Specified 

low 

(cold test) 

Distance measurement

Number of test 

pulses 

Indication, I Test pulses 

error 

DC 

voltage 

supply 

Operating 

temperature 

Actual Ref. Start End 

Taximeter 

constant, k

(pulses/ 

km) 

Distance 

tariff 

(I/km) 

Pulses % 

MPE 

% 

Specified 

high 

(dry heat) 12 V 

Specified 

low 

(cold test) 

Passed Failed 

Remarks: 

 

10 Function control tests are conducted at the specified temperatures after 16 hours exposure at each temperature limit. The test is performed 

after sufficient temperature stabilization has occurred. The change of temperature shall not exceed 1 °C/min during heating and cooling 

down. 
OIML R 21: 2007 (E) Report page .....of ..... 

75 

C.2.2 Damp heat cyclic (condensing) test (5.1.2, 5.1.3, A.5.4.2) 

At start After 3 h After 12 h At end 

Application no.: ..................... Temp: °C 

Observer: ..................... Time: hh:mm:ss 

Test Result 

Significant fault 

Temperature/humidity 

sequence11

24 h 

period 

Indication 

I Yes Yes (remarks)12

Temperature rise from 

reference at 95 % Rel. h. 0 to 3 

Specified high temperature 

at 93 % Rel. h. 3 to 12 

Temperature drop to 

reference at 95 % Rel. h. 18 to 24 

Passed Failed 

Remarks: 

 

11 All parts of the EUT are within 3 °C of their final temperature. 

12 Functional status of the instrument during and after exposure to disturbances. 
OIML R 21: 2007 (E) Report page .....of ..... 

76 

C.2.3 Function control and visual examination at ambient environmental conditions after 

static temperatures and damp heat test (7.2.2, A.4.4) 

Time measurement 

DC 

voltage 

supply 

Time 

measuring 

signal (Hz) 

Test pulses Indication, I Time signal 

error 

Test pulses 

error 

Actual Ref. Actual Ref. Start End 

Time 

tariff 

(I/h) 

Hz % Pulses % 

MPE 

% 

12 V 

Distance measurement

DC 

voltage 

supply 

Number of test 

pulses 

Indication, I Taximeter 

constant, k

(pulses/km) 

Distance 

tariff 

(I/km) 

Test pulses 

error 

MPE 

% 

Actual Ref. Start End Pulses % 

12 V 

Visible deterioration detected: Yes No 

Result: Passed Failed 

Remarks: 
OIML R 21: 2007 (E) Report page .....of ..... 

77 

C.2.4 Voltage drop below the lower voltage limit of 9 V DC (5.2.5, A.5.4.3.2) 

The results of the supply voltage limits variation test in C.1.1.1 shall be referred to and recorded with 

this test. 

At start At end 

Application no.: ...................................................... Temp: °C 

Type designation: ..................................................... Rel. h.: % 

Observer: ..................................................... Date: yyyy-mm-dd 

Time: hh:mm:ss 

Battery voltage (DC): 12 V Other battery power supply 

Unom = V Umin = V Umax = V 

% of lower value of 

voltage reduction, VL

Width of reduction 

(seconds) 

Passed Failed Remarks 

7 

14 

15 

17.5 

20 

21 

80 

30 

7 

14 

15 

17.5 

20 

21 

40 

30 

7 

14 

15 

17.5 

20 

21 

0 

30 

Passed Failed 

Remarks: 
OIML R 21: 2007 (E) Report page .....of ..... 

78 

Duration of polarity 

change (seconds) 

Registered information 

complies 

Registered information 

does not comply 

Polarity change: 

± 12 V DC 

Passed Failed 

Remarks: 

C.2.4.1 Function control and visual examination at ambient environmental conditions after 

voltage variation test (7.2.2, A.4.4) 

Time measurement 

DC 

voltage 

supply 

Time 

measuring 

signal (Hz) 

Test pulses Indication, I Time signal 

error 

Test pulses 

error 

Actual Ref. Actual Ref. Start End 

Time 

tariff 

(I/h) 

Hz % Pulses % 

MPE 

% 

12 V 

Distance measurement

DC 

Voltage 

supply 

Number of test 

pulses 

Indication, I Taximeter 

constant, k

(pulses/ 

km) 

Distance 

tariff 

(I/km) 

Test pulses 

error 

MPE 

% 

Actual Ref. Start End Pulses % 

12 V 

Visible deterioration detected: Yes No 

Result: Passed Failed 

Remarks: 
OIML R 21: 2007 (E) Report page .....of ..... 

79 

C.2.5 Vibrations test (A.5.4.4) 

Y

X

Taximeter vibration test fixture 

Figure B.3 - Set up for X axis vibration 

Y

X

Figure B.2 - Set up for Y axis vibration 

Taximeter vibration test fixture 

Y

X 

Taximeter vibration test fixture 

Z

Figure B.1 - Set up for Z axis vibration: Direction of motion is in and out of page. 
OIML R 21: 2007 (E) Report page .....of ..... 

80 

C.2.5 Vibrations test (A.5.4.4) 

Two different vibration tests (random or sinusoidal) are described below. In general, the random vibration test 

is recommended. The sinusoidal vibration test may be applied if specified by the manufacturer. 

C.2.5.1 Random vibrations in three mutually perpendicular axes (A.5.4.4.1) 

At start At end 

Application no.: ...................................................... Temp: °C 

Type designation: ..................................................... Rel. h.: % 

Observer: ..................................................... Date: yyyy-mm-dd 

Time: hh:mm:ss 

Time measurement

Time 

measuring 

signal (Hz) 

Number of test 

pulses 

Indication, I Time signal 

error 

Test pulses 

error 

DC 

Voltage 

supply 

In three 

axes13

Actual Ref. Actual Ref. Start End 

Time 

tariff 

(I/h) 

Hz % Pulses % 

MPE 

% 

First 

axis 

Second 

axis 12 V 

Third 

axis 

Distance measurement

Number of test 

pulses 

Indication, I Test pulses 

Error 

DC 

Voltage 

supply 

In three 

axes 

Actual Ref. Start End 

Taximeter 

constant, k

(pulses/ 

km) 

Distance 

tariff 

(I/km) 

Pulses % 

MPE 

% 

First 

axis 

Second 

axis 12 V 

Third 

axis 

Passed Failed 

Remarks: 

 

13 In accordance with the specifications in Table 10, apply random vibrations, over a frequency range of 10-150 Hz, to the EUT, at the specified 

ASD level, in three mutually perpendicular axes in turn, for 30 minutes per axis in each functional mode. 
OIML R 21: 2007 (E) Report page .....of ..... 

81 

C.2.5.2 Sinusoidal vibration in three mutually perpendicular axes (A.5.4.4.2) 

At start At end 

Application no.: ...................................................... Temp: °C 

Type designation: ..................................................... Rel. h.: % 

Observer: ..................................................... Date: yyyy-mm-dd 

Time: hh:mm:ss 

Time measurement

Time 

measuring 

signal (Hz) 

Number of test 

pulses 

Indication, I Time signal 

error 

Test pulses 

error 

DC 

Voltage 

supply 

In three 

axes14

Actual Ref. Actual Ref. Start End 

Time 

tariff 

(I/h) 

Hz % Pulses % 

MPE 

% 

First 

axis 

Second 

axis 12 V 

Third 

axis 

Distance measurement

Number of test 

pulses 

Indication, I Test pulses 

error 

DC 

Voltage 

supply 

In three 

axes 

Actual Ref. Start End 

Taximeter 

constant, k

(pulses/ 

km) 

Distance 

tariff 

(I/km) 

Pulses % 

MPE 

% 

First 

axis 

Second 

axis 12 V 

Third 

axis 

Passed Failed 

Remarks: 

 

14 In accordance with the specifications in Table 11, apply sinusoidal vibrations, over a frequency range of 10-150 Hz, at 1 octave/min, and at 

10 ms-2 maximum acceleration level with 20 sweep cycles per axis, in three mutually perpendicular main axes of the rigidly mounted EUT 
OIML R 21: 2007 (E) Report page .....of ..... 

82 

C.2.5.3 Function control and visual examination at ambient environmental conditions after 

vibration test (7.2.2, A.4.4) 

Time measurement

Time 

measuring 

signal (Hz) 

Number of test 

pulses 

Indication, I Time signal 

error 

Test pulses 

error 

DC 

Voltage 

supply 

Actual Ref. Actual Ref. Start End 

Time 

tariff 

(I/h) 

Hz % Pulses % 

MPE 

% 

12 V 

Distance measurement

Number of test 

pulses 

Indication, I Test pulses 

error 

DC 

Voltage 

supply 

Actual Ref. Start End 

Taximeter 

constant, k

(pulses/ 

km) 

Distance 

tariff 

(I/km) 

Pulses % 

MPE 

% 

12 V 

Visible deterioration detected Yes No 

Result: Passed Failed 

Remarks: 
OIML R 21: 2007 (E) Report page .....of ..... 

83 

C.2.6 Immunity to electromagnetic fields 

C.2.6.1 Immunity to radiated electromagnetic fields test (A.5.4.5.1) 

At start At end 

Application no.: ...................................................... Temp: °C 

Type designation: ..................................................... Rel. h.: % 

Observer: ..................................................... Date: yyyy-mm-dd 

Time: hh:mm:ss 

Disturbances MPE 

compliance Frequency 

range 

(MHz) 

Polarization 

Facing 

EUT Yes No 

Remarks 

without disturbance 

26 – 80 Front 

Right 

Left 

Vertical 

Rear 

Front 

Right 

Left 

Horizontal 

Rear 

80 - 2000 Front 

Right 

Left 

Vertical 

Rear 

Front 

Right 

Left 

Horizontal 

Rear 
OIML R 21: 2007 (E) Report page .....of ..... 

84 

Test severity 

Frequency range: 80 MHz (1) to 2000 MHz 

RF amplitude (50 Ω): 24 V/m 

Modulation: 80 % AM, 1 kHz, sine wave 

Notes: (1) Lower limit is 26 MHz if the test according to A.5.4.5.2 cannot be applied due to lack of 

I/O ports; 

(2) 24 V/m is the recommended severity level concerning electronic sub assemblies installed 

in motor vehicles (see the Automotive EMC Directive (2004/104/EC)). However, in 

accordance with national regulations a lower severity level of 12 V/m may be applied. 

Note: If EUT fails, the frequency and field strength at which this occurs must be recorded. 

Passed Failed 

Remarks: 
OIML R 21: 2007 (E) Report page .....of ..... 

85 

C.2.6.2 Immunity to conducted electromagnetic fields test (A.5.4.5.2) 

At start At end 

Application no.: ...................................................... Temp: °C 

Type designation: ..................................................... Rel. h.: % 

Observer: ..................................................... Date: yyyy-mm-dd 

Time: hh:mm:ss 

MPE 

compliance Frequency 

Range 

(MHz) 

Cable/Interface 

Level 

(Volts RMS) Yes No 

Remarks15

without disturbance 

without disturbance 

without disturbance 

without disturbance 

without disturbance 

without disturbance 

 

15 Functional status of the instrument during and after exposure to disturbances. If the EUT fails, the frequency and field strength at which 

this occurs must be recorded. 
OIML R 21: 2007 (E) Report page .....of ..... 

86 

Test severity 

Frequency range: 0.15 MHz to 80 MHz 

RF amplitude (EMF): 24 V e.m.f 

Modulation: 80 % AM, 1 kHz sine wave 

Note: 24 V is the recommended severity level concerning electronic sub assemblies installed in 

motor vehicles (see the Automotive EMC Directive (2004/104/EC)). However, in 

accordance with national regulations a lower severity level of 10 V/m may be applied. 

Passed Failed 

Remarks: 

Include a description of the setup of EUT, e.g. by photos or sketches. 

Note: If the EUT fails, the frequency and field strength at which this occurs must be recorded. 

Radiated: 

Conducted:
OIML R 21: 2007 (E) Report page .....of ..... 

87 

C.2.6.3 Electrostatic discharges (A.5.4.6) 

At start At end 

Application no.: ...................................................... Temp: °C 

Type designation: ..................................................... Rel. h.: % 

Observer: ..................................................... Date: yyyy-mm-dd 

Time: hh:mm:ss 

Contact discharge Paint penetration 

Air discharges 

Polarity16: pos neg 

The EUT shall be in operation during the test. 

Direct application 

Discharges MPE 

compliance Type Test 

voltage (kV)18

Number of 

discharges ≥ 10

Repetition 

interval (s) Yes No 

Remarks17

without disturbance 

Contact 2 

Contact 4 

Contact 6 

Air 8 

Indirect application (Horizontal coupling plane) 

Discharges MPE 

compliance Type Test 

voltage (kV) 

Number of 

discharges ≥ 10

Repetition 

interval (s) Yes No 

Remarks 

without disturbance 

Contact 2 

Contact 4 

Contact 6 

 

16 IEC 61000-4-2 specifies that the test shall be conducted with the most sensitive polarity. 

17 Functional status of the instrument during and after exposure to disturbances. Significant faults or the test point at which EUT failure 

occurs shall be recorded. 

18 6 kV is the recommended maximum level contact discharge. However, in accordance with national regulations a maximum level of 4 kV contact 

discharge may be applied.
OIML R 21: 2007 (E) Report page .....of ..... 

88 

Indirect application (Vertical coupling plane) 

Discharges MPE 

compliance Type Test 

voltage (kV) 

Number of 

discharges ≥ 10

Repetition 

interval(s) Yes No 

Remarks 

without disturbance 

Contact 2 

Contact 4 

Contact 6 

Passed Failed 

Remarks: 

Specification of test points of EUT (direct application), e.g. by photos or sketches 

a) Direct application 

Contact discharges: 

Air discharges: 

b) Indirect application 
OIML R 21: 2007 (E) Report page .....of ..... 

89 

C.2.6.4 Function control and visual examination at ambient environmental conditions after 

electrostatic discharge test (7.2.2, A.4.4) 

Time measurement

Time 

measuring 

signal (Hz) 

Number of test 

pulses 

Indication, I Time signal 

error 

Test pulses 

error 

DC 

voltage 

supply 

Actual Ref. Actual Ref. Start End 

Time 

tariff 

(I/h) 

Hz % pulses % 

MPE 

% 

12 V 

Distance measurement

Number of test 

pulses 

Indication, I Test pulses 

error 

DC 

Voltage 

supply 

Actual Ref. Start End 

Taximeter 

constant, k

(pulses/ 

km) 

Distance 

tariff 

(I/km) 

Pulses % 

MPE 

% 

12 V 

Visible deterioration detected: Yes No 

Result: Passed Failed 

Remarks: 
OIML R 21: 2007 (E) Report page .....of ..... 

90 

C.2.7 Electrical transient conduction (A.5.4.7) 

C.2.7.1 Electrical transient conduction along voltage supply lines (A.5.4.7.1) 

At start At end 

Application no.: ...................................................... Temp: °C 

Type designation: ..................................................... Rel. h.: % 

Observer: ..................................................... Date: yyyy-mm-dd 

Time: hh:mm:ss 

Exposure of the EUT to disturbances on the DC voltage supply line by direct coupling of pulses. 

DC voltage Test pulse Pulse voltage MPE compliance 

(V) Yes No 

Remarks19

1 – 100 

2a + 50 

2b20 + 10 

3a – 150 

3b + 100 

12 V 

4 – 7 

Passed Failed 

Remarks: 

 

19 Functional status of the instrument during and after exposure to test pulses 

20 Test pulse 2b is only applicable if the instrument is connected to the battery via the main (ignition) switch of the car, i.e. if the 

manufacturer has not specified that the instrument is to be connected directly (or by its own main switch) to the battery.
OIML R 21: 2007 (E) Report page .....of ..... 

91 

C.2.7.2 Electrical transient conduction via lines other than voltage supply lines (A.5.4.7.2) 

With the applicable voltage supply on, the various signal lines of the EUT are exposed to disturbances 

by capacitive/inductive coupling. 

MPE 

compliance 

DC voltage Test pulse Pulse 

voltage, Us

Yes No 

Remarks 21

Cable/interface: 

a – 60 V 

b + 40 V 

Cable/interface:

a – 60 V 

b + 40 V 

Cable/interface:

a – 60 V 

b + 40 V 

Cable/interface:

a – 60 V

b + 40 V

Cable/interface: 

a – 60 V 

12 V 

b + 40 V 

Passed Failed 

Remarks: 

 

21 Functional status of the instrument during and after exposure to test pulses 
OIML R 21: 2007 (E) Report page .....of ..... 

92 

C.2.7.3 Function control and visual examination at ambient environmental conditions after 

electrical transient conduction test (7.2.2, A.4.4) 

Time measurement

Time 

measuring 

signal (Hz) 

Number of test 

pulses 

Indication, I Time signal 

error 

Test pulses 

error 

DC 

Voltage 

supply 

Actual Ref. Actual Ref. Start End 

Time 

tariff 

(I/h) 

Hz % Pulses % 

MPE 

% 

12 V 

Distance measurement

Number of test 

pulses 

Indication, I Test pulses 

error 

DC 

Voltage 

supply 

Actual Ref. Start End 

Taximeter 

constant, k

(pulses/ 

km) 

Distance 

tariff 

(I/km) 

Pulses % 

MPE 

% 

12 V 

Visible deterioration detected: Yes No 

Result: Passed Failed 

Remarks: 
OIML R 21: 2007 (E) Report page .....of ..... 

93 

C.3 EXAMINATION OF THE CONSTRUCTION OF THE INSTRUMENT 

Use this page to indicate any description or information pertaining to the instrument, additional to that 

already contained in this report and in the accompanying national type approval or OIML Certificate. 

This may include a picture of the complete instrument, a description of its main devices, and any 

remark which could be useful for authorities responsible for the initial or subsequent verifications of 

individual instruments built according to the type. It may also include references to the manufacturer's 

description. 

Description: 

Remarks:
OIML R 21: 2007 (E) Report page .....of ..... 

94 

CHECKLIST 

The checklist has been developed based on the following principles. 

It is intended to serve as a summary of the results of examinations to be performed and not as a 

procedure. The items on this checklist are provided to recall the requirements specified in R 21 and they 

shall not be considered as a substitution for these requirements. 

For non-mandatory devices, the checklist provides space to indicate whether or not the device exists and, 

if appropriate, its type. A cross in the box for “present” indicates that the device exists and that it 

complies with the definition given in the terminology; when indicating that a device is non-existent, also 

check the boxes to indicate that the tests are not applicable. 

If appropriate, the results stated in this checklist may be supplemented by remarks given on additional 

pages. 
OIML R 21: 2007 (E) Report page .....of ..... 

95 

Application no.: .............................................. Type designation: .............................................. 

R 21 

Clause 

Test 

Clause 

Taximeters Passed Failed Remarks 

3 A.1 METROLOGICAL REQUIREMENTS 

Main function of the taximeter 

− Designed to measure the duration, and 

− To calculate the distance of a journey. 

3.1 

Calculates and displays the fare to be paid, on the basis of the 

initial fare registered on the taximeter before distance is 

traveled and the fare incrementing with fixed intervals after 

the appertaining distance and/or time is delivered. 

3.3 Taximeter accuracy conformance over time 

Manufacturer provides documented description of taximeter 

design for accuracy conformance with the metrological 

requirements of R 21 for a period of at least one year. 

Units of measurement to be used on taximeter are: 

− Time, in seconds, minutes and hours; 

− Distance, in metres (m) or kilometres (km), or as specified 

in national regulations;

3.4 

− Fare, in accordance with national regulations.

3.5.1 Temperature 

Minimum temperature range of 80 °C for the climatic 

environment. 

DC voltage supply 

12 V battery

3.5.2 

Other supply voltage Remarks

Taximeter constant, k

Taximeter constant, k is adjustable to the vehicle within the 

mpes of 3.2.1.1 (b).

k can be displayed on the taximeter as a readily accessible 

decimal number.

Every change of k is secured in accordance with 4.2.5. 

3.6 

The use of the taximeter is not possible when the change 

registration capacity defined by the manufacturer is exceeded. 

Real-time clock 

Taximeter is equipped with a real time clock which keeps 

track of the time of the day and the date. 

3.7 A.1

Time and/or the date can be used for the automatic change of 

tariffs. 
OIML R 21: 2007 (E) Report page .....of ..... 

96 

R 21 

Clause 

Test 

Clause 

Taximeters Passed Failed Remarks 

Accuracy shall be 0.02 % of the time. 

Correction for summer and winter time is performed 

automatically and complies with the requirements of 4.2.5. 

Other corrections, automatic or manual, prevented during a 

journey, unless conducted during a verification process. 

During interruption to supply voltage, real time clock 

continues to function correctly, and retains the correct time 

and date for at least one year and in accordance with national 

regulations. 

4 A.1 TECHNICAL REQUIREMENTS 

Suitability for use 

Taximeter suits the method of operation and vehicles for which 

it is intended. 

4.1 

Taximeter is of robust construction to maintain its metrological 

characteristics. 

4.2 Security of operation 

4.2.1 Fraudulent use 

No characteristics likely to facilitate fraudulent use. 

Accidental breakdown, maladjustment and inspection 

Effect of accidental breakdown or maladjustment is evident.

Any malfunction shall be clearly indicated (e.g. by a 

significant fault indication or by automatic switch off). 

4.2.2 

The absence or improper functioning of connected instruments 

shall (automatically) prevent the operation of the taximeter. 

This setting of the taximeter shall be secured. 

4.2.3 Controls and keys 

Controls and keys come to rest in intended positions and 

unambiguously marked keys. 

4.2.4 Inspection and adjustment 

Easy inspection and adjustments of the taximeter functions is 

possible. 

Securing of functions, hardware, software and pre-set controls 

− Means provided for securing taximeter functions, 

measurement data, hardware, software and pre-set 

controls, to which access, adjustment or removal is 

prohibited. 

− Security provided on all parts of the measuring system 

which cannot be sealed in any other way against 

operations liable to affect the measurement accuracy. 

Other security specified and/or provided in accordance with national regulations to ensure:

4.2.5 A.2 

(a) Any device for changing the parameters of legally 

relevant measurement data shall be secured by appropriate 

hard-software means against unintentional and accidental 

changes 
OIML R 21: 2007 (E) Report page .....of ..... 

97 

R 21 

Clause 

Test 

Clause 

Taximeters Passed Failed Remarks 

(b) Access to legally relevant functions only allowed to the 

metrological authority, e.g. by changeable code (keyword) or of a special device (hard key, etc.); 

(c) Interventions can be recorded and this information can be 

accessed and displayed; 

(d) Recorded information include the date and a means of 

identifying the authorized person making the intervention 

(see a) above); 

(e) Traceability of the interventions shall be assured for at 

least the period of time in between periodical verifications 

depending on national regulations; 

(f) Records may not be overwritten, and if the storage 

capacities for records is exhausted, no further intervention 

shall be possible without breaking a physical seal; 

(g) Protection of software functions against intentional, 

unintentional and accidental changes is provided in 

accordance with 4.11; 

(h) Protection and detection of physical tampering with 

taximeter hardware is provided (e.g. seals); 

(i) Transmission and updating of legally relevant data and/or 

software is protected against intervention in accordance 

with the requirements of 4.10, 4.11 and 5.2.3; 

(j) Securing possibilities available in taximeter allows for 

separate securing of tariff data; 

Fare calculation

The interval of fare to pay, the fare calculation method S and 

D, and the monetary symbols comply with national 

regulations. 

Remarks 

Taximeter is able to calculate fare by both method S (single 

application of tariff) and method D (double application of 

tariff) 

The option of switching between calculation methods S and D 

shall be by a secured setting. 

4.3 A.1 

Indications for fare calculation comply with 4.9.1. 

4.4 Tariff programming

Each allocated tariff may include following data:

− initial hire fee as an amount of money; 

− initial time; 

− initial distance; 

− time-tariff value as an amount of money per hour; 

− distance-tariff value as an amount of money per 

kilometre, or in accordance with national regulations; 

− supplementary charge increment, if appropriate; 

4.4.1 

− signature of the corresponding tariff data. 
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Input of tariff data

It is possible to secure the access to the level where tariff data 

can be changed in accordance with the requirements of 4.2.5.

Tariff data may be entered individually via an appropriately 

protected interface (5.2.3).

Unauthorized or unintentional tariff re-programming due to 

interfacing with other equipment shall be prevented in 

accordance with the securing requirements in 4.2.5.

If the taximeter is capable of having its tariffs re-programmed 

in advance of the effective date, those tariffs shall not become 

effective until that date.

4.4.2 

Where applicable, the tariffs shall have identifications and 

signatures of the corresponding tariff parameters. 

4.5 A.1 Operating position device

Indications in the operating positions are as follows: 

In “For Hire” (Free) operating position

Time-counting and distance-counting shall be inactive. 

In “For hire” (Free) operating position it is possible to display, when relevant, the following parameters: 

 all elements of the indicator display; 

 the contents of totalizers (see 4.7); 

 the taximeter constant, k, expressed in pulses per 

kilometre; 

 the contents of the event counters (see 4.2.5); 

 the tariff data of each allocated tariff (see 4.4.1); 

 signatures of the corresponding tariff parameters; 

 date and time; 

 software version number and/or checksum. 

The above parameters shall not be displayed for more than 

10 seconds when the vehicle is moving. 

4.5.1 

Other indications in “For Hire” (Free) operating position are 

permitted in accordance with national regulations, and shall 

not be interpreted as fare or supplement indication and their 

use is subject to the requirements of 4.2. 

In “Hired” (Occupied) operating position

Time-counting and distance-counting shall be activated. 

Indications in “Hired” (Occupied) operating position shall be in the following order: 

(a) The initial charge; 

(b) The first fare indication, followed by subsequent fare 

indication changes corresponding to the initial and then 

successive equal time intervals or distances specified in 

the applied tariff; 

4.5.2 

Indications in “Hired” operating position include the distance 

and time displays and comply with the quality of indication 

requirements in 4.9.1 and where appropriate, comply with 
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national regulations. 

In “Stopped” (To Pay) operating position

Fare calculation based on time is disabled (i.e. time-counting 

is inactive).

Indications in “Stopped” (To Pay) operating position are: 

(a) The fare to be paid for the journey; or

(b) Any supplementary charge for an extra service, entered by 

manual command, is displayed separately from the 

indicated fare.

In the case of b) above: 

 Taximeter may indicate temporarily the value of the 

fare including the supplementary charge; 

 Indication of the supplement is made by figures with 

a height not more than that of the figures indicating 

the fare. 

4.5.3 

Indications in the “Stopped” (To Pay) operating position 

comply with 4.9.1.

In the “Measure” operating position

In calculation method D the distance and duration of the 

journey are measured and displayed in real time on a separate 

indicator.

Indications in the “Measure” operating position are: 

(a) Time measured in hours with smallest increment of 

30 seconds; 

(b) Resolution of measured distance is better than or equal to 

0.1 km; 

(c) Both time and duration readings may be given at the same 

time, or may be recalled one after the other by means of 

the operating position device; 

4.5.4 A.1 

(d) Period of use shown as hh:mm:ss and the indicated unit of 

measurement shall comply with 3.9.1 to prevent 

confusion. 

Additional requirements for operating position device

(a) In “Stopped” (To Pay) operating position fare indication 

is readable for at least 10 seconds and during this time it 

shall not be possible to change the operating position; 

(b) Design and setting of the operating position device 

ensures that any change in operating positions and their 

indications comply with the appropriate requirements for 

securing in 4.2.5; 

4.6 A.1 

(c) It is not possible to place the taximeter in any operating 

positions other than those mentioned above, unless 

otherwise specified in national regulations. 

Non-resettable totalizers

Clear and unambiguous display of: 

(a) Total distance traveled by the taxi; 

(b) Total distance traveled when hired; 

4.7 A.1 

(c) Total number of journeys; 
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(d) Total amount of money charged as supplements; 

(e) Total amount of money charged as fare. 

Other data totalled in accordance with national regulations 

complies with 4.9.1.

Values saved under conditions of supply voltage loss are 

included in the total and shall be stored for at least one year.

Totalized values displayed for a maximum of 10 seconds, or 

for a time in accordance with national regulations.

Totalizers have a minimum number of digits (e.g. 8 digits) in 

accordance with national regulations.

The tariff data may be triggered by the:

 distance of the journey;

 duration of the journey;

 time of day;

 date;

 day of the week, including special days (e.g. Christmas,

 Easter, ...) if relevant;

4.8 A.1

 any alteration of tariff data complies with 4.2.5.

4.9 A.1 Indicating and printing

Quality of reading:

Primary indications shall be by means of a display. 

Reading of primary indications reliable, easy and unambiguous 

under conditions of normal use including in daylight and at 

night. 

Figures forming the primary indications shall be of a size 

equal to or higher than 10 mm in height, and of a shape and 

clarity for easy reading. 

Primary indications contain names or symbols of the units of 

measurement and comply with the requirements of 3.4. 

Indications of interest to the passenger are suitably identified 

and readable from a distance of at least 2 metres. 

Digital indication shall display at least one figure beginning at 

the extreme right. 

4.9.1 

Decimal fraction shall be separated from its integer by a 

decimal sign (comma or dot), with the indication showing at 

least one figure to the left of the sign and all figures to the 

right. 

Printing device Present [ ] Not present [ ] 

Printing is clear and permanent for the intended use. Printed 

figures shall be clear, legible and unambiguous. 

4.9.2 

If printing takes place, the name or the symbol of the unit of 

measurement shall be either to the right of the value or above a 

column of values, or placed in accordance with national 

regulations. 
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Multiple copies of the print-out containing the same data must 

be marked “copy” or “duplicate”. 

Minimum printout from each measurement operation shall be 

dependent upon the application of the taximeter and in 

accordance with national regulations. 

In general the printout information may include the 

programmed tariff, fare, supplementary charge, distance and 

duration of the journey, date and the time of the journey. 

Data storage:

(a) In taximeter memory device; 

(b) External (removable) storage device. 

In accordance with national regulations there shall be adequate security to ensure that: 

(a) Securing of legally relevant software stored or transmitted 

between storage devices comply with the appropriate 

requirements of 4.11; 

(b) The legally relevant measurement data stored or 

transmitted shall be accompanied by all relevant 

information necessary to reconstruct an earlier 

measurement for future legally relevant use; 

(c) External storage device identification and security 

attributes shall be verified to ensure integrity and 

authenticity; 

(d) Exchangeable storage media is sealed against 

unauthorized removal in accordance with 4.2.5; 

(e) For long term storage of legally relevant data, the data 

must be stored automatically when the measurement is 

concluded. The long-term storage must have a capacity 

which is sufficient for the intended use. 

4.10 A.1

(f) When the storage is full, new data may replace oldest data 

provided that the owner of the old data has given authority 

to overwrite the old data and it complies with the 

appropriate requirements of 4.2.5 and 4.11. 

Software

Distinct separation between the legally relevant and nonrelevant software. 4.11 A.1 

Legally relevant software is identified by the manufacturer.

In accordance with national regulations software documentation submitted with the instrument includes: 

(a) Description of the legally relevant software;

(b) Description of the accuracy of the measuring algorithms;

(c) Description of the user interface, menus and dialogues;

(d) The unambiguous software identification;

(e) Overview of the system hardware, e.g. (e.g. rounding 

algorithm when calculating the distance or price); 

(f) Means of securing the software;

(g) Operating manual;

4.11.1 

(h) Other relevant information regarding the software 

characteristics of the taximeter. 

Remarks 
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Securing of legally relevant software

In accordance with national regulations there shall be adequate security to ensure that: 

(a) The legally relevant software shall be adequately 

protected against accidental or intentional changes by 

means of an audit trail or an event counter providing 

information record of the changes to the software; 

(b) The legally relevant software is assigned with a software 

identification which shall be adapted in the case of every 

software change that may affect the functions and 

accuracy of the taximeter. Software identification shall be 

easily provided by the taximeter; 

(c) The transmission, changing and updating of the legally 

relevant software shall be secured and comply with the 

relevant requirements and conditions of 5.2.3; 

(d) It shall be possible to access and display the information 

in the audit trail records; the records shall include the date 

and a means of identifying the authorized person making 

the intervention (see a) above); the traceability of the 

interventions shall be assured for at least the period of 

time in between periodical verifications depending on 

national legislation; 

4.11.2 

(e) Legally relevant records may not be overwritten, and if 

the storage capacities for legally relevant records are 

exhausted, no further intervention shall be possible 

without breaking a physical seal. 

Descriptive markings:

Taximeters shall bear the following markings, variable according to national regulations: 

 Name or identification mark of manufacturer; 

 Name or identification mark of the importer (if 

applicable); 

 Serial number and type designation of the instrument 

(if applicable); 

 Type approval sign and/or number of the type 

examination certificate; 

 Relevant data in respect of the conditions of use; 

 year of manufacture; 

 Specified range of the taximeter constant, k (if 

applicable) in pulses per kilometre; 

4.12 A.2 

 Software identification (if applicable). 

4.12.1 Supplementary markings

Are required Remarks 

Presentation of descriptive markings

 Indelible; 

 Size, shape and clarity that allows easy reading; 

 Grouped together in a clearly visible place; 

 Descriptive plate bearing markings to be sealed, unless 

it cannot be removed without being destroyed; 

4.12.2 

 Shown in national languageor 
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 Shown in form of adequate internationally agreed and 

published pictograms and signs; 

The descriptive markings simultaneously displayed by a 

software solution either permanently or on manual commend.

In the case of software solution:

The taximeter constant, k, and real-time shall be displayed as 

long as the taximeter is switched on;

The other markings may be accessed and displayed by a 

simple manual commend (e.g. a specific keystroke);

It shall be described in the type approval certificate;

Software controlled display markings need not be repeated on 

the data plate, if they are shown on or indicated near the 

display of the measurement result, with the exception of the 

following markings which shall be shown on the data plate: 

 taximeter constant, k and the date shall be shown on 

the display; 

 type approval sign in accordance with national 

requirements; 

 name or identification mark of the manufacturer. 

Verification marks

In accordance with national regulations initial verification markings include: 

 Verification authority identification;

 Date of verification;

4.13 A.2 

 Other verification markings specified in accordance 

with national regulations.

Position of verification marks

Part where verification marks are located cannot be removed 

from the instrument without damaging the marks.

Allows easy application of marks without changing the 

metrological qualities of the instrument.

4.13.1 

Visible when the instrument is in service.

5 ELECTRONIC REQUIREMENTS

5.1.3 Disturbances

Indication of significant faults in the display does not lead to 

confusion with other messages.

5.2 A.1 Functional requirements

5.2.1 Indicator display test:

Upon switch-on, all relevant signs of indicator are active and 

non-active for sufficient time to be checked by operator.

Acting upon a significant fault

 Either the instrument is made inoperative automatically; 

or

5.2.2 A.1 

 Visual or audible indication is provided automatically 

and continues until the user takes action or the fault 
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disappears.

Interface(s):

A taximeter shall be able to supply the following data through appropriate protective interfaces: 

 Operation position: “For Hire”, “Hired” or 

“Stopped”; 

 Totalizer data according to 4.7; 

 General information: e.g. date of securing, vehicle 

identification, real time, tariff identification; 

 Fare information for a journey: e.g. total charged, 

fare, calculation of the fare, supplement charge, date, 

start time, finish time, distance traveled; 

5.2.3

 Tariff(s) information: e.g. parameters of tariff(s). 

In accordance with national regulations documentation on interfaces submitted with the instrument 

includes: 

 Description of the interface; 

 Identification of the interface (e.g. RS232, USB, 

interface number or label, etc.); 

 A list of all commands (e.g. menu items in case of a 

user interface, or commands that are accepted by the 

software of the device, received via each 

communication interface); 

 A brief description of their meaning and their effect 

on the functions and data of the measuring 

instrument; 

5.2.3.1 

 Other relevant information regarding taximeter 

interfaces. 

Interfaces security: 

An interface through which the functions mentioned in 5.2.3 

cannot be performed or initiated, need not be secured. Remarks 

In accordance with national regulations there shall be adequate security to ensure that: 

(a) Interfaces shall not allow the metrological functions of the 

taximeter and its legally relevant software and data to be 

inadmissibly influenced by other interconnected 

instruments, or by disturbances acting on the interface; 

(b) The legally relevant data and metrological functions are 

protected against accidental or intentional changes by a 

protective interface; 

(c) The legally relevant functions in the taximeter’s interfaces 

secured in accordance with the appropriate requirements 

for securing hardware in 4.2.5 and software in 4.11; 

(d) The legally relevant parts of the connected instrument, 

and functions performed or initiated by the connected 

instrument are included in the initial or subsequent 

verification; 

5.2.3.2 

(e) It shall be easily possible to verify the authenticity and 

integrity of data transmitted to and/or from the taximeter 

and the connected instrument. 

5.2.4 Taximeter test connector

For performing the functional tests in A.4 the taximeter is 

equipped with a test connector, the functioning of which is 

checked to ensure that it is capable of processing the signals in 
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Table 1. 

Test connector shall be easily accessible after installation in a 

vehicle provided that it is secured against unauthorized access 

in accordance with 4.2.5. 

If the taximeter is connected to a network in the car (e.g. CAN 

bus), there shall be the possibility for an input and output for 

the distance information. In that case the taximeter does not 

work with pulses but with digital distance information. 

Under conditions of voltage drop below the lower voltage limit:

Taximeter continues to function correctly or resume its correct 

functioning without loss of data prior to the temporary voltage 

drop (e.g. less than 20 seconds);

Abort an existing measurement and switch to the “For Hire” 

operating position if the period of voltage drop is greater than 

20 seconds; In this case, the taximeter shall resume its correct 

functioning and retain the correct stored data concerning the 

journey;

Show a significant fault or is automatically put out of service if 

the voltage drop is for a lengthy period.

5.2.5 A.1 

If disconnected from the supply voltage, the taximeter shall 

keep the totalized value information for at least one year or for 

a period set in accordance with national regulations.

6 METROLOGICAL CONTROLS

Type approval

Documentation submitted for type approval includes:

 Metrological characteristics of the taximeter (3); 

 Technical and electronic specifications (4, 5); 

 Functional description of the taximeter and its 

devices; 

 Drawings, diagrams, photo of the instrument 

explaining its construction and operation; 

 Description and application of securing components, 

controls, fault indication function, etc. (4.2, 4.10, 5.2); 

 Interfaces (types, intended use, immunity to external 

influences instructions (4.2.5, 5.2.3); 

 General software information (4.11, 4.12.2); 

 Printing devices (4.9.2); 

 Data storage devices (4.10); 

 Drawing or photo of the instrument showing the 

principle and the location of control marks, securing 

marks, descriptive and verification marks (4.2.5, 

4.12); 

 List of tariffs provided on the taximeter; 

 Any document or other evidence that the design and 

construction of the taximeter and devices comply 

with the requirements of this Recommendation; 

6.2 

 Operating instructions, operating manual. 
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Type evaluation

Type evaluation conducted on one or more taximeters 

submitted in a form suitable for laboratory tests. 

Submitted documents examined; and tests carried out to verify 

that the taximeter complies with the: 

(a) Metrological requirements in Clause 2, with reference to 

the appropriate mpes and the operating conditions 

specified by the manufacturer; 

(b) Technical requirements in Clause 4; 

(c) Electronic requirements in Clause 5. 

Tests: 

 Conducted in a manner that prevents an unnecessary 

commitment of resources, and permit the results of 

the tests to be assessed for initial verification; 

 Other appropriate tests in accordance with national 

regulations to verify compliance with R 21; 

 Accept, with the consent of the applicant, test data 

obtained from other metrological authorities without 

repeating tests; 

 Under the normal rated operating conditions for 

which the taximeter is intended; 

 Functioning of the taximeter determined in 

accordance with Clause 7 and Annex A; 

 Influence factors shall be applied to the taximeter as 

specified in 3.5 and Annex A; 

 Either on the premises of the metrological authority 

to which the application has been submitted, or in 

any other suitable place agreed between the 

metrological authority concerned and the applicant; 

6.2.2

 With equipment and personnel supplied by the 

applicant. 

6.3 Initial verification

General 

 Tests conducted in accordance with national 

regulations; 

 Tests conducted in a manner that prevents an 

unnecessary commitment of resources, and permits 

the results of the tests to be assessed for initial 

verification; 

 Other appropriate tests in accordance with national 

regulations to verify compliance with the 

metrological and technical requirements of this 

Recommendation; 

6.3.1 

 Accept, with the consent of the applicant, test data 

obtained from other metrological authorities without 

repeating tests. 

To verify compliance with the following: 

 Appropriate maximum permissible errors in 3.2.1; 

 For correct functioning of all devices, e.g. distance 

transducer, taximeter, real-time clock; 

6.3.2 

 For construction material and design, as far as they 
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are of metrological relevance; 

 If appropriate a list of the tests performed; 

 Secured tariffs if applicable (depending on national 

regulations). 

Initial verification

Tests conducted on the taximeter and including all devices 

which form the assembly as intended for normal operational 

use. 

The verification procedure may be carried out in two stages: 

 where the first stage shall allow for easy examination 

of the tariff parameters and the distance measurement 

without the influence of the vehicle; and 

 the second stage shall comprise all examinations of 

which the outcome is dependent on tests of a vehicleinstalled taximeter. 

Visual inspection 

Before testing, the taximeter shall be visually inspected for: 

 physical metrological characteristics, i.e. 

measurement units, real-time clock; 

 identification of software if applicable; 

 prescribed markings and positions for verification 

and control marks. 

6.3.3

If location and conditions of use of the instrument are known, 

it should be considered whether they are appropriate.

Remarks 

Marking and securing. 

According to national legislation, initial verification may be 

testified by verification marks as specified in 4.13.

6.3.4
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Use this space to detail remarks from the checklist 
OIML R 21: 2007 (E) 

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BIBLIOGRAPHY 

Below are references to Publications of the International Electrotechnical Commission (IEC), the 

International Organization for Standardization (ISO) and the OIML, where mention is made in this 

Recommendation. 

Ref. Standards and reference documents Description 

[1] International Vocabulary of Basic and 

General Terms in Metrology (VIM) (1993) Vocabulary, prepared by a joint working group 

consisting of experts appointed by BIPM, IEC, 

IFCC, ISO, IUPAC, IUPAP and OIML. 

[2] International Vocabulary of Terms in Legal 

Metrology, OIML, Paris (2000) 

Vocabulary including only the concepts used in 

the field of legal metrology. These concepts 

concern the activities of the legal metrology 

service, the relevant documents as well as other 

problems linked with this activity. Also included 

in this Vocabulary are certain concepts of a 

general character which have been drawn from the 

VIM. 

[3] OIML B 3 (2003) 

OIML Certificate System for Measuring 

Instruments (formerly OIML P 1) 

Provides rules for issuing, registering and using 

OIML Certificates of conformity. 

[4] OIML D 11 (2004) 

General requirements for electronic 

measuring instruments 

Provides guidance for establishing appropriate 

metrological performance testing requirements for 

influence quantities that may affect the measuring 

instruments covered by International 

Recommendations. 

[5] IEC 60068-2-1 (1990-05) with 

Amendments 1 (1993-02) and 2 (1994-06) 

Basic environmental testing procedures - 

Part 2: Tests, Test Ad: Cold, for heat 

dissipating equipment under test (EUT), 

with gradual change of temperature. 

Concerns cold tests on both non-heat-dissipating 

and heat dissipating specimens. 

[6] OIML D 19 (1988) Provides advice, procedures and influencing 

factors on type evaluation and type approval. 

[7] OIML D 20 (1988) 

Initial and subsequent verification of 

measuring instruments and processes 

Provides advice, procedures and influencing 

factors on the choice between alternative 

approaches to verification and the procedures to 

be followed in the course of verification. 

[8] IEC 60068-2-2 (1974-01) with 

Amendments 1 (1993-02) and 2 (1994-05). 

Environmental testing Part 2: Tests, Test B: 

Dry heat 

Contains test Ba: dry heat for non heat dissipating 

specimen with sudden change of temperature; test 

Bb dry heat for non heat dissipating specimen 

with gradual change of temperature; tests Bc: dry 

heat for heat dissipating specimen with sudden 

change of temperature; test Bd: dry heat for heat 

dissipating specimen with gradual change of 

temperature. 
OIML R 21: 2007 (E) 

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Ref. Standards and reference documents Description 

The 1987 reprint includes IEC no. 62-2-2A 

[9] IEC 60068-3-1 (1974-01) + Supplement A 

(1978-01): 

Environmental testing Part 3 Background 

information, Section 1: Cold and dry heat 

tests 

Gives background information for Tests A: Cold 

(IEC 68-2-1), and Tests B: Dry heat (IEC 68-2-2). 

Includes appendices on the effect of: chamber size 

on the surface temperature of a specimen when no 

forced air circulation is used; airflow on chamber 

conditions and on surface temperatures of test 

specimens; wire termination dimensions and 

material on surface temperature of a component; 

measurements of temperature, air velocity and 

emission coefficient. 

Supplement A gives additional information for 

cases where temperature stability is not achieved 

during the test. 

[10] IEC 60068-3-4 (2001-08) 

Environmental testing - Part 3-4: 

Supporting documentation and guidance - 

Damp heat tests 

Provides the necessary information to assist in 

preparing relevant specifications, such as 

standards for components or equipment, in order 

to select appropriate tests and test severities for 

specific products and, in some cases, specific 

types of application. The object of damp heat tests 

is to determine the ability of products to withstand 

the stresses occurring in a high relative humidity 

environment, with or without condensation, and 

with special regard to variations of electrical and 

mechanical characteristics. Damp heat tests may 

also be utilized to check the resistance of a 

specimen to some forms of corrosion attack. 

[11] IEC 60068-2-30 Ed. 3.0 (2005-08) 

Environmental testing - Part 2: Tests. Test 

Db and guidance: Damp heat, cyclic (12 + 

12-hour cycle). 

Determines the suitability of components, 

equipment or other articles for use, transportation 

and storage under conditions of high humidity - 

combined with cyclic temperature changes and, in 

general, producing condensation on the surface of 

the specimen. If the test is being used to verify the 

performance of a specimen whilst it is being 

transported or stored in packaging then the 

packaging will normally be fitted when the test 

conditions are being applied. For small, low mass 

specimens, it may be difficult to produce 

condensation on the surface of the specimen using 

this procedure; users should consider the use of an 

alternative procedure such as that given in IEC 

60068-2-38. 

[12] ISO 16750-2 (2003) Road vehicles – Environmental conditions and 

testing for electrical and electronic equipment. 

Part 2: Electrical loads. 

[13] IEC 60068-3-8 (2003-08) Environmental testing: Supporting documentation 

and guidance – Selecting amongst vibration tests. 
OIML R 21: 2007 (E) 

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Ref. Standards and reference documents Description 

[14] IEC 60068-2-64 Ed. 1.0 (1993-05) Environmental testing - Part 2: Test methods - 

Test Fh: Vibration, broad-band random (digital 

control) and guidance. 

[15] IEC 60068-2-47 Ed. 3.0 (2005-04) 

Environmental testing - Part 2-47: Test 

methods - Mounting of components, 

equipment and other articles for vibration, 

impact and similar dynamic tests. 

This standard provides methods for mounting 

products, whether packaged or unpackaged, as 

well as mounting requirements for equipment and 

other articles, for the series of dynamic tests in 

IEC 60068-2, that is impact (Test E), vibration 

(Test F) and acceleration, steady-state (Test G). 

When they are fastened to the test apparatus and 

subjected to these tests, whether packaged or 

unpackaged, they are referred to as specimens. 

[16] IEC 60068-2-6 (1995-03), with Correction 

1 (1995-03) 

Environmental testing – Part 2: Tests-Test Fc: 

Vibration (sinusoidal). 

[17] IEC 61000-4-3 Ed. 3.0 (2006-02) 

Electromagnetic Compatibility (EMC) - 

Part 4: Testing and measurement techniques 

- Section 3: Radiated, radio-frequency, 

electromagnetic field immunity test. 

Is applicable to the immunity requirements of 

electrical and electronic equipment to radiated 

electromagnetic energy. It establishes test levels 

and the required test procedures. The object of 

this standard is to establish a common reference 

for evaluating the immunity of electrical and 

electronic equipment when subjected to radiated, 

radiofrequency electromagnetic fields. The test 

method documented in this part of IEC 61000 

describes a consistent method to assess the 

immunity of an equipment or system against a 

defined phenomenon. This part deals with 

immunity tests related to the protection against RF 

electromagnetic fields from any source. Particular 

considerations are devoted to the protection 

against radio-frequency emissions from digital 

radiotelephones and other RF emitting devices. 

It has the status of a basic EMC publication. 

[18] IEC 61000-4-6 (2003-05) with Amendment 

2 (2006-03) 

Consolidated Edition 2.2 (2006-05) 

Electromagnetic compatibility (EMC) 

Part 4: Testing and measurement 

techniques. Section 6: Immunity to 

conducted disturbances, induced by radiofrequency fields 

Relates to the conducted immunity requirements 

of electrical and electronic equipment to 

electromagnetic disturbances coming from 

intended radio-frequency (RF) transmitters in the 

frequency range 9 kHz up to 80 MHz. Equipment 

not having at least one conducting cable (such as 

mains supply, signal line or earth connection), 

which can couple the equipment to the disturbing 

RF fields is excluded. The object of this standard 

is to establish a common reference for evaluating 

the functional immunity of electrical and 

electronic equipment when subjected to conducted 

disturbances induced by radio-frequency fields. 

The test method documented in this part of IEC 

61000 describes a consistent method to assess the 

immunity of an equipment or system against a 

defined phenomenon. 
OIML R 21: 2007 (E) 

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Ref. Standards and reference documents Description 

[19] IEC 61000-4-2 (1995-01) with Amendment 

1 (1998-01) and Amendment 2 (2000-11) 

Basic EMC Publication Electromagnetic 

compatibility (EMC) Part 4: Testing and 

measurement techniques Section 2: 

Electrostatic discharge immunity test. 

Consolidated Edition: 

IEC 61000-4-2 (2001-04) Ed. 1.2 

This publication is based on IEC 60801-2 (second 

edition: 1991). It relates to the immunity 

requirements and test methods for electrical and 

electronic equipment subjected to static electricity 

discharges, from operators directly, and to 

adjacent objects. It additionally defines ranges of 

test levels which relate to different environmental 

and installation conditions and establishes test 

procedures. The object of this standard is to 

establish a common and reproducible basis for 

evaluating the performance of electrical and 

electronic equipment when subjected to 

electrostatic discharges. In addition, it includes 

electrostatic discharges which may occur from 

personnel to objects near vital equipment. 

[20] ISO 7637-2 (2004) Road vehicles - Electrical disturbance by 

conduction and coupling - Part 2: Electrical 

transient conduction along supply lines only. 

[21] ISO 7637-3 (1995) with correction 1, 

(1995) Road vehicles - Electrical disturbance by 

conduction and coupling - Part 3: Passenger cars 

and light commercial vehicles with nominal 12 V 

supply voltage and commercial vehicles with 

24 V supply voltage - electrical transient 

transmission by capacitive and inductive coupling 

via lines other than supply lines.