The 1790D-T4T0 from Allen-Bradley belongs to the CompactBlock LDX I/O family. This module provides four dedicated thermocouple input channels. It captures small millivolt signals generated by thermocouples, converts them into digital temperature readings, and transmits the data over a DeviceNet network.
You can connect up to four independent temperature sensors to this module. It supports common thermocouple types including B, E, J, K, R, S, T, and N. The input voltage range is -76.50 mV to +76.50 mV. With a 16-bit resolution of 0.1 °C per bit, the 1790D-T4T0 delivers accurate temperature measurements.
Number of inputs: 4 channels
Input range: -76.50 mV to +76.50 mV
Supported thermocouples: Type B, E, J, K, R, S, T, N, and 10 µV
Resolution: 16 bits (0.1 °C/bit or 0.1 °F/bit)
Converter type: 20-bit Sigma-Delta modulation
Data format: 16-bit integer (2’s complement)
Module scan time: 140 ms per channel (at 60 Hz notch filter)
Overall accuracy: 0.2% full scale @ 0…55 °C
Input impedance: 5 MΩ
Cold junction compensation range: 0…70 °C
Open wire detection: Supported, shown as "out of range" message
The 1790D-T4T0 allows you to select a notch filter frequency to reduce noise. Available options are:
10 Hz (default)
25 Hz
50 Hz
60 Hz
100 Hz
250 Hz
500 Hz
This module needs two separate power supplies.
DeviceNet power: 24V dc nominal (voltage range 11…28.8V dc). Maximum power dissipation is 1.2 W @ 28.8V dc.
Field power: 24V dc nominal (voltage range 21.6…26.4V dc). Maximum power dissipation is 1.5 W @ 26.4V dc.
I/O to logic: Photocoupler isolation, tested at 1250V ac rms for 60 seconds
DeviceNet to logic: Nonisolated
Field power: Nonisolated
Weight: 0.50 lbs (0.23 kg)
Operating temperature: 0…55 °C
Indicators: 4 red/green I/O status LEDs
Wiring terminal: M3.0 screw type, maximum torque 7 lb-in
Conductor type: Copper or copper-clad aluminum only
Follow these steps to install the 1790D-T4T0 correctly.
Disconnect DeviceNet network power before wiring.
Connect field power (21.6…26.4V dc) to the designated terminals.
Wire each thermocouple to its corresponding input channel. Use proper extension wire for the thermocouple type.
Tighten terminal screws to 7 lb-in maximum. Do not exceed this torque.
Configure the notch filter frequency and thermocouple type via software.
Apply power and verify the I/O status LEDs.
Furthermore, use shielded thermocouple extension cables to minimize electrical noise. Keep thermocouple wiring away from power cables and motor drives.
1790D-T4T0 module (1 unit)
Terminal block (factory installed)
Quick start guide
Note: No certificates or warranty documents are included in the package.
We ship worldwide via FedEx, UPS, or DHL. Orders are dispatched within 1-2 business days.
1. Which thermocouple types work with the 1790D-T4T0?
The 1790D-T4T0 supports Type B, E, J, K, R, S, T, N, and 10 µV thermocouples.
2. Does this module detect broken thermocouple wires?
Yes. Open wire detection is supported. The module reports an "out of range" message to the processor when a wire breaks.
3. What is the scan time for all four channels?
Each channel scans in 140 milliseconds at the 60 Hz notch filter setting. For all four channels, the total scan time is 560 milliseconds.
4. Can I change the noise filter frequency?
Yes. You can select from 10 Hz, 25 Hz, 50 Hz, 60 Hz, 100 Hz, 250 Hz, or 500 Hz. The default setting is 10 Hz.
5. What is the cold junction compensation range?
The internal cold junction compensation operates from 0…70 °C. This ensures accurate readings regardless of ambient temperature at the module.
| Brand Name | Allen-Bradley |
| Model No. | 1790D-T4T0 |
| Product Type | Thermocouple Input Module |
| hasMerchantReturnPolicy | Adjust according to reality |
| Shippingdetails | Adjust according to reality |
