Thermocouple Transmitter, Ethernet & 4-20 mA Outputs

Exceptional linearity & accuracy at high update rates. DIN Rail mounted, digitally programmable.

Ethernet transmitter


  • Ethernet Serial Data I/O, Modbus TCP or TDM ASCII protocol
  • 4-20 mA or 0-10V transmitter output, 16 bits, jumper selectable, isolated
  • Dual 120 mA solid state relays for alarm or control, isolated
  • Factory calibrated for thermocouple types J, K, T, E, N, R, S each in one range
  • User selectable input span from entire thermocouple range down to 15.0°
  • Analog output resolution 0.0015% of span (16 bits), accuracy ±0.02% of span
  • Fast update rate to 50 or 60 per second
  • Universal 85-264 Vac / 90-300 Vdc or 10-48 Vdc / 12-32 Vac power
  • DIN rail mount housing only 22.5 mm wide, detachable screw-clamp connectors

The thermocouple transmitter provides a linearized, highly accurate, stable and repeatable transmitter output for thermocouple types J, K, T, E, N, R or S. The thermocouple type and temperature range, specified in °C or °F, are user-selectable. The temperature range can be as wide as the entire span of the thermocouple type, or as narrow as 150 counts (such as 15.0°), limited only by considerations of electrical noise and digital filtering time constants.

Thermocouple signal conditioner board

Digital calibration of all thermocouple ranges is performed the factory, with calibration data stored in EEPROM on the signal conditioner board. This allows signal conditioner boards and ranges to be changed in the field with no need for recalibration. Cold junction compensation automatically corrects for temperature variations at the thermocouple reference junction at the transmitter. Open sensor indication is standard and may be set up to indicate either upscale or downscale.

Fast read rate at up to 50 or 60 conversions per second while integrating the signal over a full power line cycle is provided by Concurrent Slope (Pat 5,262,780) analog-to-digital conversion. High read rate is ideal for peak or valley capture and for real-time computer interface and control.

Standard features of LTE transmitters include:

  • Ethernet I/O, isolated. Supported protocols are Modbus RTU and ASCII (tunneled via Modbus TCP) and TDM ASCII. The latter is simpler than the Modbus protocol and is recommended when all devices are s. Note that RS232 or RS485 data I/O in lieu of Ethernet is provided by LT Series transmitters.
  • 4-20 mA, 0-20 mA or 0-10V analog transmitter output, isolated, jumper-selectable and user scalable. All selections provide 16-bit (0.0015%) resolution of output span and 0.02% output accuracy of a reading from -99,999 to +99,999 counts that is also transmitted digitally. Output isolation from signal and power grounds eliminates potential ground loop problems. The supply can drive 20 mA into a 500 ohm (or lower) load for 10V compliance, or 10V into a 5K ohm (or higher) load for 2 mA compliance.
  • Dual solid state relays, isolated. Available for local alarm or control. Rated 120 mA at 130 Vac or 180 Vdc.
  • Universal 85-264 Vac power. Low-voltage 10-48 Vdc or 12-32 Vac power is optional.

Discovery and configuration of Ethernet Nodes is easily achieved with TDM's Node Manager Software, and the discovered transmitters can then be programmed using TDM's Instrument Setup Software. Both softwares run on a PC under MS Windows and can be downloaded from this website at no charge.

 Ethernet network by TD Micronic
Ethernet & 4-20 mA Output Thermocouple Temperature Transmitter
TC Types Range Conformity Error
J -210°C to +760°C (-347°F to +1400°F) ±0.09°C (±0.16°F)
K -244°C to +1372°C (-408°F to +2501°F) ±0.1°C (±0.17°F)
L 0°C to +400°C (32°F to 752°F)
-257°C to 0°C (-430°F to +32°F)
±0.03°C (±0.05°F)
±0.2°C (±0.36°F)
E -240°C to +1000°C (-400°F to +1830°F) ±0.18°C (±0.32°F)
N -245°C to +1300°C (-410°F to +2370°F) ±0.10°C (±0.17°F)
R -45°C to +1768°C (-49°F to +3214°F) ±0.17°C (±0.31°F)
S -46°C to +1768°C (-51°F to +3213°F) ±0.12°C (±0.22°F)
Analog Input
Calibration NIST Monograph 125 (IPTS-68)
Input resistance 1 GΩ
Input current 100 pA
Max lead resistance 1 kΩ max for rated accuracy
Overall accuracy ±0.01 of full scale ±2 counts
Span tempco ±0.003% of reading/°C
Ref junction tempco °0.02 deg/deg
Overvoltage protection 125 Vac
NMR at 50/60 Hz 80 dB plus selectable filter from 80 ms to 9.6 s time constant
CMR, DC-60 Hz 120 dB with 500Ω imbalance
CMV, DC-60 Hz 250 Vac from power and earth grounds
Open sensor indication 0 mA or > 20 mA output, selectable
Analog Output (standard)
Output Levels 4-20 mA, 0-20 mA, 0-10 Vdc (jumper selectable)
Compliance, 4-20 mA 10V (0-500Ω load)
Compliance, 0-10V 2 mA (5 kΩ load or higher)
Output Resolution 16 bits (65,536 steps)
Output Accuracy 0.02% of output span plus conversion accuracy
Output Isolation 250V rms working, 2.3 kV rms per 1 minute test
Step response time 50 ms
Ethernet Data I/O (standard)
Type 10/100 Base-T Ethernet per IEEE 802.3
Data Rates 300, 600, 1200, 2400, 4800, 9600, 19200 baud
Output Isolation 250V rms working, 2.3 kV rms per 1 min test
Serial Protocols Modbus TCP, Modbus RTU, Modbus ASCII, TDM ASCII
Modbus Compliance Modbus over Serial Line Specification V1.0 (2002)
Digital Addresses 247 for Modbus, 31 for TDM ASCII
Dual Relay Output (standard)
Relay Type Two solid state relays, SPST, normally open, Form A
Load Rating 120 mA at 140 Vac or 180 Vdc
Power Input
Standard Power 85-264 Vac or 90-300 Vdc
Low Power Option 10-48 Vdc or 12-32 Vac
Power Frequency DC or 47-63 Hz
Power Isolation 250V rms working, 2.3 kV rms per 1 min test
Power Consumption 2W typical, 3W with max excitation output
Dimensions 129 x 104 x 22.5 mm case
Mounting 35 mm rail per DIN EN 50022
Electrical Connections Plug-in screw-clamp connectors
Operating Temperature 0°C to 55°C
Storage Temperature -40°C to 85°C
Relative Humidity 95% at 40°C, non-condensing
Cooling Required Mount transmitters with ventilation holes at top and bottom. Leave 6 mm (1/4") between transmitters, or force air with a fan.

Ethernet & 4-20 mA Output Thermocouple Temperature Transmitter

LTE Ethernet transmitter pinout, analog input

Operation as a Fast ON/OFF Controller or Supervisory Monitor

Temperature controller operation of  temperature meters and transmitters

With the optional dual solid state relay output option, which has a typical response time of only 17 ms, temperature meters and transmitters can serve as extremely fast and accurate ON/OFF controllers for closed-loop temperature control. They can also serve as supervisory process monitors and provide alarms or shutoffs when processes exceed normal limits.

Multiple setpoint operating modes are individually selectable for each relay, as explained in the dual-setpoint controller page. Relay duty cycles and chatter can be minimized with programmable hysteresis and time delays. A band deviation operating mode can be selected for each relay, where an alarm is generated whenever the reading is a selected number of counts above or below the setpoint. The relay modes have to be non-latching, since 4-20 mA temperature transmitters do not offer external reset.

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