SL MD-220
Optical Transmittance Analyzer
SPECIFICATIONSFEATURES


2 Channel, digital interface
Works in stop and go traffic
Up to 30dB dynamic range
Flexible optocoupler digital outputs (up to60V)
Completely software driven – easily
adaptable for custom applications
Optimized for toll applications
Capable of dual tire detection
RS-232 Output for use with Signal Viewer
Software and Data Log capabilities
4 triggered outputs (2 for sensors, 1 for dualtire, and 1 for sensor failure)

SENSOR SOLUTIONS /// MD-220

2 channel digital interface
Flexible optocoupler digital outputs
Direct external control
Minimal power consumption
Adjustable trigger level impulse duration
Sensor failure indication

The Sensor Line MD-220 is a two-channel digital
opto-electronic interface for Sensor Line's fiber optic loadsensors. This two-channel interface supplies light to two
fiber optic sensors, monitors the amount of lighttransmitted through the sensors and detects smallchanges caused by loads applied to the sensors. With its
advanced circuitry, the interface can detect a load on asensor for as long as it is applied to the sensor.
The MD-220 incorporates a TI MSP-430 embedded
microcontroller, programmable via a JTAG interface. It
has a 10-wire screw-clip interface with power supply
terminals and four floating optocoupler outputs. It also has
a RS-232 interface data transmission and troubleshooting.
Direct external control is possible through the use of an 8way SIL switch, two jumpers and a reset switch. For
quicker troubleshooting, six LED status displays show thefunction of the interface and there are five easily
accessible test points for analog measurements.
Power consumption has been minimized by circuitrythat operates the transmitter diodes in series while
independently controlling the current through each diode.
The MD-220 uses near infrared diodes which give eachchannel a dynamic range of 30 dB.

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Optical Transmittance Analyzer

TECHNICAL DATA
HardwareHardware Version

2.0c STD-1

Number of Channels
Size2
3.54 x 4.33 x 0.75 in (100 x 110 x 19 mm)
10-wire screw terminal block
RS-232, 3-wire*
5 test points
SMA 905
850 nm (NIR)
30 dB (NIR)
80% at 77°F (25°C)-40 to 185°F (-40 to 85°C)+12 to +24 VDC< 140 mA

Electrical Connections
Optical connections
LED Peak Output Wavelength
Maximum Sensor Loss
Relative Humidity
Temperature Range
Supply Voltage
Supply Current
Analog Output at Test Points
Optocoupler Outputs max.
RS-232 connector
Velocity Range
Feeder Length
Comparative Laser ClassEMV/EMI

0-10 V
OFF: 50 V/<1 uA
ON: 5 V/50 mA (250 mW @ 25°C)
9-pin DSUB male
Up to 155 mph (250 km/h)
Up to 820 ft (250 meters)
3A (NIR, sensor disconnected)
Meets CE-requirements* selectable with SIL switch
Software
Program Name
Program Version
Program cycle time

MD220STD
1.3500 μs ± 5%

Watchdog expiration time

4 ms
0.2%, 0.4%, 0.8%, 1.6%change of light transmittance*
0%, 6.25%, 12.5%, 25%, 50%of load signal*± 2 digits
3 program cycles (1.5 ms)
3 program cycles (1.5 ms) /40 program cycles (20 ms)**
80 program cycles (40 ms)**
30 s
9600 / 19200 / 115200 Baud*81N (no parity)

Thresholds
Adaptive Threshold
Triggering

Hysteresis
Minimum input ON time
Minimum output ON time

RS-232

Maximum output ON time
Baud Rate
Data Bits
Stop Bits
Parity* selectable with SIL switch** selectable with jumper J1SENSOR SOLUTIONS /// MD-220

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SL MD-220
Optical Transmittance Analyzer

MECHANICAL DIMENSIONS in mm (in)System Terminal

Fiber Optic SMA 905 Receptacles

90 (3.543)

Channel 1
ReceiverThrough Holes Ø3.1 (.122)
Transmitter 1

Channel 1
Transmitter
Transmitter 2

Channel 2
Transmitter
Receiver 2

Channel 2
ReceiverRS-232Connector.

SIL-Switch

Test Points

Status LEDs

+12..24VDC
GND
AUX2AUX2+
AUX1AUX1+TRG2TRG2+
TRG1TRG1+100 (3.937)

JTAGConnector

Receiver 1

9 8 7 6 5 4 3 2 1 0110 (4.331)

Jumpers

ResetSwitch120 (4.724)

Maximum Height 19 (.748)
Model Number

Part Number

Laser

SL MD-200-IR

1007062-2

IR

SENSOR SOLUTIONS /// MD-220

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SL MD-220
Optical Transmittance Analyzer

PRINCIPLES OF OPERATION

The drawing above is a simple circuit diagram of one channel. When the photodiode is illuminated with light fromthe sensor it proportionally sinks a current to the incoming light power. This causes the output of the OPAMP togo high so the current is supplied across the 7.5 MΩ resistor. When the light becomes too bright the OPAMP
output is clipped, and the controller supplies additional current via the DAC and the 470 k resistor until theOPAMP output is “unclipped.”
Small changes of photo current are amplified by the OPAMP by a factor of 7.5 MΩ (7.5 V/μA). The controllermeasures this voltage ("Analog Voltage" or VANAx) as well as the voltage produced by the A-D converter("Monitor Voltage" or VMONx) with a resolution of 12 Bits. An additional A-D converter controls the light power fed
into the sensor

NORTH AMERICA

ASIA

Measurement Specialties, Inc.,a TE Connectivity Company
Phone +1-800-522-6752
Email: customercare.hmpt@te.com

Measurement Specialties (China), Ltd.,a TE Connectivity Company
Phone: +86-400-820-6015
Email: customercare.chdu@te.com

TE.com/sensorsolutions
Measurement Specialties, Inc., a TE Connectivity company.
Accustar, American Sensor Technologies, AST, ATEXIS, DEUTSCH, IdentiCal, TruBlue, KPSI, Krystal Bond, Microfused, UltraStable, Measurement Specialties, MEAS, Schaevitz, TE
Connectivity, TE, and the TE connectivity (logo) are trademarks of the TE Connectivity Ltd. family of companies. Other logos, product and company names mentioned herein may be
trademarks of their respective owners.
The information given herein, including drawings, illustrations and schematics which are intended for illustration purposes only, is believed to be reliable. However, TE Connectivity makes
no warranties as to its accuracy or completeness and disclaims any liability in connection with its use. TE Connectivity‘s obligations shall only be as set forth in TE Connectivity‘s StandardTerms and Conditions of Sale for this product and in no case will TE Connectivity be liable for any incidental, indirect or consequential damages arising out of the sale, resale, use ormisuse of the product. Users of TE Connectivity products should make their own evaluation to determine the suitability of each such product for the specific application.

SENSOR SOLUTIONS /// MD-220

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