Product Overview
The Allen-Bradley 1790D-T4R0 CompactBlock LDX I/O 4-channel input RTD base module is a distribution block that collects information from Resistance Temperature Detectors (RTDs) and transmits the collected data to central processors via the DeviceNet communication network. It handles up to 4 resistance inputs with a range from 1 ohm to 625 ohms. Depending on the RTD sensors, this module can achieve a resolution of 100 milliohms to 0.1 degrees Celsius. Data travels through DeviceNet media in a digital format of 16-bit integers, at a module scan time of 8 milliseconds per channel.
Technical Specifications Breakdown
Key parameters for the 1790D-T4R0 are listed below for quick reference:
| Feature | Specification |
|---|---|
| Inputs per module | 4 channel, RTD/Resistance Input |
| Input range | 1…625 Ω |
| Resolution | 16 bits across 625 Ω, 0.1 °C/bit or 0.1°F/bit (RTD Sensors); 20-bit Sigma-Delta modulation converter |
| Module scan time | 8 ms/channel @ Notch Filter = 60 Hz |
| Overall accuracy | 0.2% Full scale @ 0…55 °C |
| DeviceNet power supply voltage | 24V dc nom; range 11…28.8V dc |
| Field power supply voltage | 24V dc nom; range 21.6…26.4V dc (+10%) |
| Power dissipation (DeviceNet) | 1.2 W max @ 28.8V dc |
| Power dissipation (Field) | 1.5 W max @ 26.4V dc |
| Weight | 0.44 lbs (0.20 kg) |
Industry Applications
The 16-bit resolution and 0.1 °C accuracy support precise control, reducing waste and improving product quality.
Installation & Setup Guidance
Mount the 1790D-T4R0 on a DIN rail or using screw mounting. Connect DeviceNet power (24V dc nominal, 11…28.8V dc range) and field power (24V dc nominal, 21.6…26.4V dc). Use copper or copper-clad aluminum conductors with M3.0 terminal block screws torqued to 7 lb-in maximum. Configure the notch filter (10 Hz default, selectable up to 500 Hz) to match line frequency and reduce noise.
Maintenance & Reliability
Periodically inspect wiring connections and verify that the module's LED indicators (4 red/green I/O status) show normal operation. Keep the ambient temperature within 0…55 °C to maintain 0.2% full-scale accuracy. The module's low power dissipation (1.2 W max for DeviceNet, 1.5 W max for field) minimizes heat buildup in enclosures.
Compatibility & Integration
The 1790D-T4R0 communicates exclusively via DeviceNet, using 16-bit integer data format. It supports a wide range of RTD sensors (100 Ω Pt, 200 Ω Pt, 500 Ω Pt, 100 Ω Nickel, 120 Ω Nickel, 200 Ω Nickel, 500 Ω Nickel) with α = 0.00385 or 0.003916. Open wire detection is supported and reported as an "out of range" signal.
Selection Guide & Purchasing Advice
When selecting an RTD input module, consider the number of measurement points and required accuracy. AutoDCSTech stocks this module and can advise on lifecycle status and availability. Please verify current lifecycle status and availability with AutoDCSTech before ordering.
Troubleshooting & Common Issues
If the module reports "out of range" signals, check for open wiring or sensor faults. Verify that the DeviceNet power supply is within 11…28.8V dc and field power within 21.6…26.4V dc. If communication fails, inspect the DeviceNet cable and terminator resistors. The module's 8 ms scan time per channel (at 60 Hz notch filter) is normal; adjust the notch filter if noise is suspected.
Availability & Condition at AutoDCSTech
| Part Number | 1790D-T4R0 |
|---|---|
| Availability | In Stock |
| Condition | New |
| Warranty | One Year |
| Origin | US |
