Product Overview
When temperature accuracy stalls production, the 1756-IR12 from Allen-Bradley delivers reliable RTD measurement for ControlLogix systems. This analog input module packs 12 non-isolated channels into a single chassis slot, giving you dense temperature sensing without expanding your footprint. Part of the Bulletin 1756 line, it handles general-purpose I/O with 24-bit resolution and a Sigma-Delta conversion method.
Technical Specifications
| Specification | Value |
|---|---|
| Module Type | Analog input, 3-wire RTD |
| Channels | 12, non-isolated |
| Resolution | 24-bit |
| Input Ranges | 1–500, 2–1000, 4–2000, 8–4000 Ohms |
| Isolation Voltage | 250 V continuous |
| Current Draw at 5.1 VDC | 200 mA (Series A), 210 mA (Series B) |
| Current Draw at 24 VDC | 70 mA |
| Backplane Power | 2.7 W (Series A), 2.75 W (Series B) |
| Operating Temperature | 0 to 60 °C (32 to 140 °F) |
| Scan Time | 50 ms minimum |
| Data Format | IEEE 32-bit floating point |
| Overvoltage Protection | ±30 VDC |
What These Specs Mean in Practice
The 24-bit resolution translates to precise temperature readings, critical when processes demand tight control. With four Ohm ranges, you can match platinum, nickel, or copper RTD sensors without swapping hardware. The 250 V continuous isolation protects your backplane from field surges, while the 50 ms scan time keeps your control loop responsive.
Where the 1756-IR12 Fits
Oil and gas operations rely on accurate temperature data for heat exchangers, compressor monitoring, and pipeline custody transfer. The 1756-IR12 handles these applications with 12 channels per module, reducing card count and cabinet space. Food processing and pharmaceutical plants also benefit from its 3-wire RTD support, which compensates for lead resistance in long cable runs.
Integration and Compatibility
The module mounts directly in a ControlLogix chassis and communicates over the backplane. It supports software-configurable electronic keying and mechanical RTB keying. Compatible removable terminal blocks include the 1756-TBCH and 1756-TBS6H. For wiring into your existing ControlLogix network, confirm cable and terminal block requirements with your supplier.
Maintenance and Reliability
RTD input modules have no moving parts, so wear is minimal. Focus on environmental factors: keep cabinet temperature within the 0 to 60 °C range and protect against moisture. Periodically inspect terminal connections for corrosion or looseness. The status LED provides quick health indication. For safety-related applications, follow the manufacturer’s safety manual and inspect periodically.
Selection Checklist
Before ordering the 1756-IR12, verify your sensor type (RTD vs. thermocouple), required input range, and chassis slot availability. Confirm your ControlLogix firmware revision supports this module. If you need spares when you need them, Oil AutoTech offers fast dispatch, worldwide. Contact Oil AutoTech today for pricing and availability.
Please verify current lifecycle status and availability with Oil AutoTech before ordering.
