WEB-TEMP
Web-Enabled Sensor Measurement

Specifications

Document Revision 1.3
February 2013
© Copyright 2013

WEB-TEMP Specifications
All specifications are subject to change without notice.
Typical for 25 °C unless otherwise specified.
Specifications in italic text are guaranteed by design.

Analog input
Table 1. Generic analog input specifications
Parameter

Condition

Specification

A/D converters
Number of channels
Input isolation
Channel configuration
Differential input voltage range

Absolute maximum input
voltage

Thermocouple
RTD
Thermistor
Semiconductor sensor±C0x through ±C7x relative to
AGND

Input impedance
Input leakage current
Common mode rejection ratio
ADC resolution
ADC No missing codes
Input couplingWarm-up time
Open thermocouple detect

CJC sensor accuracy

Open thermocouple detect disabledOpen thermocouple detect enabled
fIN = 60 Hz

15 °C to 35 °C
0 °C to 55 °C

2Four dual 24-bit, Sigma-Delta type
8 differential
500 VDC minimum between field wiring andpower supply input.
Software programmable to match sensor type±0.080 V
0 V to 0.5 V
0 V to 2 V
0 V to 2.5 V±25 V (power on)±40 V (power off)
5 GΩ (power on)
1 MΩ (power off)
30 nA max
105 nA max
100 dB min
24 bits
24 bitsDC
30 minutes min
Automatically enabled when the channel pair isconfigured for thermocouple sensor.
The maximum open detection time is 3 seconds.
–0.75 °C to 0.5 °C max–1.5 °C to 1.25 °C max

Specifications

WEB-TEMP

Channel configurations
Table 2. Channel configuration specifications
Sensor Category

Condition

Max number of
sensors (all channels
configured alike)

Disabled

All temperature input channels are disconnected from screw
terminals and internally connected to AGND.

See Note 3

Thermocouple (Note 1)
Semiconductor sensor(Note 1)
RTD and Thermistor(Note 1)

8 differential channels
8 differential channels
2-wire input configuration with a single sensor per channel pair2-wire input configuration with two sensors per channel pair
3-wire configuration with a single sensor per channel pair
4-wire input configuration with a single sensor per channel pair
4-wire input configuration with two sensors per channel pair

4 differential channels
8 differential channels
4 differential channels
4 differential channels
8 differential channels

Note 1: Internally, the WEB-TEMP has four, dual-channel, fully differential A/Ds providing a total of eight

differential channels. The analog input channels are therefore configured in four channel pairs with
CH0/CH1 sensor inputs, CH2/CH3 sensor inputs, CH4/CH5 sensor inputs, and CH6/CH7 sensor
inputs paired together. This "channel-pairing" requires the analog input channel pairs be configured tomonitor the same category of temperature sensor. Mixing different sensor types of the same category is
permissible, such as a type J thermocouple on channel 0 and a type T thermocouple on channel 1.
Note 2: Channel configuration information is stored on a EEPROM external to the isolated microcontroller by
the firmware whenever any item is modified. Modification is performed by commands issued over
Ethernet from an external application, and the configuration is made non-volatile through the use of the
EEPROM.
Note 3: The factory default configuration is Disabled. The Disabled mode disconnects the analog inputs fromthe terminal blocks and internally grounds (AGND) all of the A/D inputs. This mode also disables eachof the current excitation sources.

Compatible sensors
Table 3. Compatible sensor type specifications
Parameter

Specification

Thermocouple

J: –210 °C to 1200 °C
K: –270 °C to 1372 °C
R: –50 °C to 1768 °C
S: –50 °C to 1768 °C
T: –270 °C to 400 °C
N: –270 °C to 1300 °C
E: –270 °C to 1000 °C
B: 0 °C to 1820 °C
100 Ω PT (DIN 43760: 0.00385 ohms/ohm/°C)
100 Ω PT (SAMA: 0.003911 ohms/ohm/°C)
100 Ω PT (ITS-90/IEC751:0.0038505 ohms/ohm/°C)Standard 2,252 Ω through 30,000 Ω
LM35, TMP35 or equivalent

RTD

Thermistor
Semiconductor / IC3

Specifications

WEB-TEMP

Accuracy
Thermocouple measurement accuracy
Table 4. Thermocouple accuracy specifications, including CJC measurement error. All specifications are (±).
SensorType

Sensor temperature(°C)

Accuracy error
maximum (°C)

Accuracy error typical (°C)

Tempco (°C/°C)

J

–210
0
1200
–210
0
1372
–50
250
1768
–50
250
1768
250
700
1820
–200
0
1000
–200
0
400
–200
0
1300

3.098
1.282
1.178
3.318
1.292
1.495
1.892
0.853
0.734
2.010
0.844
0.612
2.199
0.824
0.471
3.050
1.465
1.010
3.226
1.334
0.856
3.406
1.300
0.978

1.762
0.724
0.684
1.843
0.730
0.799
1.058
0.479
0.416
1.124
0.475
0.347
2.192
0.821
0.469
1.708
0.826
0.564
1.797
0.754
0.496
1.897
0.735
0.571

0.040

K

S

R

B

E

T

N

0.045

0.027

0.025

0.004

0.038

0.045

0.035

Note 4: Thermocouple measurement accuracy specifications include polynomial linearization, cold-junction

compensation and system noise. These specs are for one year, or 3000 operating hours, whichevercomes first, and for operation of the WEB-TEMP between 15 °C and 35 °C after 30 minute warm-up.
The tempco should be applied to the accuracy specifications for operation at an ambient temperature
outside of the 15 °C and 35 °C range. There are total of four CJC sensors, two per side of the module.
Each CJC sensor is dedicated to one of the four channel pairs. The accuracy listed above assumes thescrew terminals are at the same temperature as the CJC sensor. Errors shown do not include inherent
thermocouple error. Contact your thermocouple supplier for details on the actual thermocouple
accuracy error.
Note 5: Thermocouples must be connected to the WEB-TEMP such that they are floating with respect to
AGND. The AGND pins are isolated from earth ground. You can connect thermocouple sensors tovoltages referenced to earth ground as long as the isolation between the AGND pins and earth groundis maintained.
Note 6: When thermocouples are attached to conductive surfaces, the voltage differential between multiple
thermocouples must remain within ±1.4V. For best results, we recommend using insulated or
ungrounded thermocouples when possible.

4

Specifications

WEB-TEMP

Semiconductor sensor measurement accuracy
Table 5. Semiconductor sensor accuracy specifications
Sensor Type

Temperature Range (°C)

Maximum Accuracy Error (°C)

LM35, TMP35 or equivalent–40 to 150±0.50Note 7: Error shown does not include errors of the sensor itself. These specs are for one year while operationof the WEB-TEMP unit is between 15 °C and 35 °C. Contact your sensor supplier for details on theactual sensor error limitations.

RTD measurement accuracy
Table 6. RTD measurement accuracy specifications
RTD

Sensor temperature(°C)

Accuracy error (°C)
maximum

Accuracy error (°C)
typicalTempco (°C/°C)

PT100, DIN,
US or ITS-90

–200
–150
–100
0
100
300
600

2.913
1.201
0.482
0.261
0.269
0.287
0.318

2.784
1.070
0.349
0.124
0.127
0.136
0.150

0.001
0.001
0.001
0.001
0.001
0.001
0.001

Note 8: Error shown does not include errors of the sensor itself. The sensor linearization is performed using a

Callendar-Van Dusen linearization algorithm. These specs are for one year while operation of thedevice is between 15 °C and 35 °C. The accuracy and tempco specifications include the accuracy of
the Callendar-Van Dusen linearization algorithm. The specification does not include lead resistanceerrors for 2-wire RTD connections. Contact your sensor supplier for details on the actual sensor error
limitations.
Note 9: Resistance values greater than 660 Ω cannot be measured by the WEB-TEMP in the RTD mode. The
660 Ω resistance limit includes the total resistance across the current excitation (±Ix) pins, which is thesum of the RTD resistance and the lead resistances.
Note 10:
For accurate three wire compensation, the individual lead resistances connected to the ±Ix pins
must be of equal ohmic value. To ensure this, use connection leads of equal lengths.

Thermistor measurement accuracy
Table 7. Thermistor measurement accuracy specifications
Thermistor

Sensortemperature (°C)

Accuracy error
maximum (°C)

Accuracy error
typical (°C)

Tempco (°C/°C)

2252 Ω

–40
0
50
120
–35
0
50
120
–25
0
50
120
–10
0

0.001
0.021
0.263
3.473
0.001
0.009
0.115
1.535
0.001
0.005
0.060
0.771
0.001
0.002

0.0007
0.008
0.130
1.750
0.0006
0.004
0.049
0.658
0.0005
0.002
0.028
0.328
0.0005
0.001

0.001
0.001
0.001
0.001
0.001
0.001
0.001
0.001
0.001
0.001
0.001
0.001
0.001
0.001

5000 Ω

10000 Ω30000 Ω5

Specifications

WEB-TEMP

Thermistor

Note 11:

Sensortemperature (°C)

Accuracy error
maximum (°C)

Accuracy error
typical (°C)

Tempco (°C/°C)

50
120

0.019
0.267

0.009
0.128

0.001
0.001

Error shown does not include errors of the sensor itself. The sensor linearization is performed
using a Steinhart-Hart linearization algorithm. The accuracy and tempco specifications include theaccuracy of the Callendar-Van Dusen linearization algorithm. These specifications are for one year
while operation of the device is between 15 °C and 35 °C. The specification does not include leadresistance errors for 2-wire thermistor connections. Contact your sensor supplier for details on theactual sensor error limitations. Total thermistor resistance on any given channel pair must not exceed
180 kΩ. Typical resistance values at various temperatures for supported thermistors are shown in Table
8.
Table 8. Typical thermistor resistance specifications

Temp (°C)

2252 Ω
thermistor

3000 Ω
thermistor

5 kΩ
thermistor

10 kΩ
thermistor

30 kΩ
thermistor

–40
–35
–30
–25
–20
–15
–10
–5
0

76 kΩ
55 kΩ
40 kΩ
29 kΩ
22 kΩ
16 kΩ
12 kΩ
9.5 kΩ
7.4 kΩ

101 kΩ
73 kΩ
53 kΩ
39 kΩ
29 kΩ
22 kΩ
17 kΩ
13 kΩ
9.8 kΩ

168 kΩ
121 kΩ
88 kΩ
65 kΩ
49 kΩ
36 kΩ
28 kΩ
21 kΩ
16 kΩ

240 kΩ (Note 12)
179 kΩ
135 kΩ
103 kΩ
79 kΩ
61 kΩ
48 kΩ
37 kΩ
29 kΩ

885 kΩ (Note 12)649 kΩ (Note 12)481 kΩ (Note 12)
360 kΩ (Note 12)271 kΩ (Note 12)
206 kΩ (Note 12)
158 kΩ
122 kΩ
95 kΩ

Resistance values greater than 180 kΩ cannot be measured by the WEB-TEMP in the thermistor
mode. The 180 kΩ resistance limit includes the total resistance across the current excitation (±Ix) pins,
which is the sum of the thermistor resistance and the lead resistances.
Note 13:
For accurate three wire compensation, the individual lead resistances connected to the ±Ix pins
must be of equal ohmic value. To ensure this, use connection leads of equal lengths.
Note 12:

Throughput rate
Table 9. Throughput rate specifications
Number of input channels

Maximum throughput

1
2
3
4
5
6
7
8

2 S/s
2 S/s on each channel, 4 S/s total
2 S/s on each channel, 6 S/s total
2 S/s on each channel, 8 S/s total
2 S/s on each channel, 10 S/s total
2 S/s on each channel, 12 S/s total
2 S/s on each channel, 14 S/s total
2 S/s on each channel, 16 S/s total

Note 14:

The analog inputs are configured to run continuously. Each channel is sampled twice per second.
The maximum latency between when a sample is acquired and the temperature data is provided by the
Ethernet unit is approximately 0.5 seconds.

6

Specifications

WEB-TEMP

Digital input/output
Table 10. Digital input/output specifications
Parameter

Specification

Digital type
Number of I/O
Configuration

CMOS
8 (DIO0 through DIO7)
Independently configured for input or output.
Switch selectable output voltages: +5 V and +3.3 V
Power on reset is Input mode except when bits are configured to operate as
alarms.

Power on conditions
Pull-up/pull-down configuration

Digital I/O transfer rate (software paced)
Input high voltage (+5 V mode)
Input high voltage (+3.3 V mode)
Input low voltage (+5 V mode)
Input low voltage (+3.3 V mode)
Output low voltage (IOL = 2.5 mA)
Output high voltage (IOH = –2.5 mA)
Note 15:

All pins are connected to 47 kΩ resistors that share a common point accessible
at Pin 22 of the device (PU/D). This pin is floating by default and is userconfigurable via external connection. For pull-up mode, connect this pin to pin
21 (+5V). For pull-down mode, connect this pin to Pin 48 (GND).
 Digital input: 50 port reads or single bit reads per second, typ.
 Digital output: 100 port writes or single bit writes per second, typ.
4 V min, 5.5 V absolute max
2.64 V min, 5.5 V absolute max
1 V max, –0.3 V absolute min
0.66 V max, –0.3 V absolute min
0.6 V max
4.3 V min (+5 V mode), 2.7 V (+3.3 V mode)

Ground pins on the device labeled GND are isolated from AGND pins and from earth ground.

Temperature alarms
Table 11. Temperature alarm specifications
Parameter

Specification

Number of alarms
Alarm functionality

8 (one per digital I/O line)
Each alarm controls its associated digital I/O line as an alarm output. The input to each
alarm may be any of the analog temperature input channels. When an alarm is enabled, its
associated I/O line is set to output and driven to the appropriate state determined by thealarm options and input temperature. The alarm configurations are stored in non-volatilememory and are loaded at power on.
 Alarm when input temperature > T1
 Alarm when input temperature > T1, reset alarm when input temperature goes below T2
 Alarm when input temperature < T1
 Alarm when input temperature < T1, reset alarm when input temperature goes above T2
 Alarm when input temperature is < T1 or > T2
T1 and T2 may be independently set for each alarm.
 Disabled, digital I/O line may be used for normal operation
 Enabled, active high output. The DIO line goes high when an alarm condition is met.
 Enabled, active low output. The DIO line goes low when an alarm condition is met.
1 second

Alarm input modes

Alarm output modes

Alarm update rate

MemoryTable 12. Memory specifications
Parameter

Specification

EEPROM
FLASH

512 bytes for sensor configuration
2 MB for device configuration and website storage

7

Specifications

WEB-TEMP

Microcontroller
Table 13. Microcontroller specifications
Parameter

Specification

Type

One high-performance 8-bit RISC microcontroller (isolated)
One high-performance 16-bit RISC microcontroller (non-isolated)

Power
Table 14. Power specifications
Parameter

Condition

Specification

Supply current (Note 17)External power input(Note 16)

Continuous mode

External power supply(included)
Voltage supervisor limits

MCC p/n PS-5V2AEPS

440 mA max+5 VDC ± 5%(+5 VDC power supply provided)+5VDC, 10 W, 5% regulation

4.75 V > Vext or Vext > 5.25 V
4.75 V < Vext < 5.25 V
Available at +5V screw terminal
Available at +5V screw terminalPWR LED = Off (power fault)
PWR LED = On
4.65 V min, 5.25 V max
10 mA max

User output voltage range
User output current
available

Voltage specification applies at barrel plug power input. The power supply provided with theboard meets this specification at the rated total power supply current. If a different power supply isused, small line resistances could cause significant voltage drop between the power supply and thebarrel plug input.
Note 17:
This is the total current requirement for the WEB-TEMP which includes up to 20 mA for theLEDs and 10 mA for the user voltage output.
Note 16:

Network
Ethernet compliance
Table 15. Ethernet compliance specifications
Parameter

Specification

Device type
Device compatibility

IEEE 802.3 Ethernet 10Base-T
IEEE 802.3-2003 10 Mpbs Media Access Control

Ethernet connection
Table 16. Ethernet connection specifications
Parameter

Specification

Ethernet type
Connector
Cable
Length
MAC address

10Base-T
RJ-45, 8 position
CAT-5 shielded, unshielded twisted pair
100 meters max
00:12:71:Cx:xx:xx, where xxxxx is the device serial number

8Specifications

WEB-TEMP

Network factory default settings
Table 17. Factory default specifications
Parameter

Specification

Factory default IP address
Factory default subnet mask
Factory default Gateway
Factory default DHCP setting
Factory default user nameFactory default password
Web server

192.168.0.101
255.255.255.0
192.168.0.1
Enabled"webtemp""mccdaq"
EnabledNetwork protocols
Table 18. Factory default specifications
Parameter

Specification

Protocols implemented

IP, ARP, ICMP, DHCP, UDP, TCP, NBNS, HTTP
Protocols using UDP or TCP for transport communicate on their IETF assigned
ports, for example HTTP on TCP port 80.
UDP port 54211
TCP port 54267
TCP port 49152-65535 (not including 54267)"webtemp_xxxxx", where xxxxx is the device serial number
Via NBNS (responds to b-node broadcasts, therefore only available on the local
subnet)3

UDP messaging protocol
TCP downloading protocol
HTTP 1.0 alternate port
Network name
Network name publication
Max number of simultaneous HTTP
connections
Max number of non-HTTP TCP
sockets

5

Network security
Table 19. Factory default specifications
Parameter

Specification

Security implementation

IP address based session manager with user-name/password login for
configuration and control transactions (data is not secured.)
5 minutes with no activity
Base64The default web page does not support encryption if Javascript is disabled in the
web browser.
Denial of service attacks, user-name/password spoofing, script probing and simple
decryption

Session timeout
User-name/password encryption

Vulnerabilities

9Specifications

WEB-TEMP

LED displays and the factory reset button
Table 20. LED and button configurations
Parameter

Specification

POWER/COMM LED (top)4.75 V < Vext < 5.25 V
On
Vext < 4.75 V, Vext > 5.25 V Off (power fault)
Blinks during microcontroller communications.
On when a valid Ethernet connection is established.
Blinks when an Ethernet packet is sent or received.
Press for 3 seconds to restore the factory default network settings.
When pressed for 3 seconds, the POWER LED turns off for a short time,
indicating that a reset is in process. When the POWER LED turns back on, thereset is complete and the factory default network settings are restored.

LINK/ACTTIVITY LED (bottom)
Factory reset button

Current excitation outputs (Ix+)
Table 21. Current excitation output specifications
Parameter

Specification

Configuration

4 dedicated pairs:±IA: CH0/CH1±IB: CH2/CH3±IC: CH4/CH5±ID: CH6/CH7
Thermistor: 10 µA typ
RTD: 210 µA typ±5% typ
200 ppm/°C
2.1 ppm/V max
0.3 ppm/V typ
3.90 V max–0.03 V min

Current excitation output ranges
Tolerance
DriftLine regulation
Load regulation
Output compliance voltage(relative to AGND pins)

The WEB-TEMP has four current excitation outputs, with ±IA dedicated to the CH0/CH1 analog
inputs, ±IB dedicated to CH2/CH3, ±IC dedicated to CH4/CH5, and ±ID dedicated to CH6/CH7. The
excitation output currents should always be used in this dedicated configuration.
Note 19:
The current excitation outputs are automatically configured based on the sensor selected(thermistor or RTD).
Note 18:

Environmental
Table 22. Environmental specifications
Parameter

Specification

Operating temperature range
Storage temperature range
Humidity

0 to 55 ° C–40 to 85 ° C
0 to 90% non-condensing

Mechanical
Table 23. Mechanical specifications
Parameter

Specification

Dimensions (L × W × H)

128.52 x 88.39 × 35.56 mm (5.06 × 3.48 × 1.43 ft)

10Specifications

WEB-TEMP

Screw terminal connector
Table 24. Screw terminal connector specifications
Parameter

Specification

Connector type
Wire gauge range

Screw terminal
16 AWG to 30 AWG
Table 25. Screw terminal pinout

Pin
1
2
3
4
5
6
7
8
9
10

Signal Name
IA+
NC
C0H
C0L
4W01
IC01
C1H
C1L
AGND
IA–

Pin Description
CH0/CH1 current excitation source
No connection
CH0 sensor input (+)
CH0 sensor input (–)
CH0/CH1 4-wire, 2 sensor common
CH0/CH1 2-sensor common
CH1 sensor input (+)
CH1 sensor input (–)
Analog ground
CH0/CH1 current excitation return

Pin
27
28
29
30
31
32
33
34
35
36

Signal Name
ID–
AGND
C7L
C7H
IC67
4W67
C6L
C6H
NC
ID+

Pin Description
CH6/CH7 current excitation return
Analog groundCH7 sensor input (–)
CH7 sensor input (+)
CH6/CH7 2 sensor common
CH6/CH7 4-wire, 2 sensor common
CH6 sensor input (–)
CH6 sensor input (+)
No connection
CH6/CH7 current excitation source

11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26

IB+
NC
C2H
C2L
4W23
IC23
C3H
C3L
AGND
IB–
+5V
PU/D
DIO0
DIO1
DIO2
DIO3

CH2/CH3 current excitation source
No connection
CH2 sensor input (+)
CH2 sensor input (–)
CH2/CH3 4-wire, 2 sensor common
CH2/CH3 2 sensor common
CH3 sensor input (+)
CH3 sensor input (–)
Analog groundCH2/CH3 current excitation return+5V output
Pull-up/down for digital outputs
DIO channel 0
DIO channel 1
DIO channel 2
DIO channel 3

37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52

IC–
AGND
C5L
C5H
IC45
4W45
C4L
C4H
NC
IC+
NC
GND
DIO7
DIO6
DIO5
DIO4

CH4/CH5 current excitation return
Analog groundCH5 sensor input (–)
CH5 sensor input (+)
CH4/CH5 2 sensor common
CH4/CH5 4-wire, 2 sensor common
CH4 sensor input (–)
CH4 sensor input (+)
No connection
CH4/CH5 current excitation source
No connection
Digital ground
DIO channel 7
DIO channel 6
DIO channel 5
DIO channel 4

11

Measurement Computing Corporation
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Suite 1008
Norton, Massachusetts 02766(508) 946-5100
Fax: (508) 946-9500
E-mail: info@mccdaq.com
www.mccdaq.com
WEB-TEMP-spec.docx