Allen-Bradley 1756-IR6I ControlLogix RTD Input Module

Configured for high-precision temperature measurement in ControlLogix chassis platforms, the Allen-Bradley 1756-IR6I (1756-IR6I Analog RTD Module) provides direct physical/electrical execution. The module digitizes resistance changes across 6 individually isolated RTD input channels to process thermal data from Platinum and Nickel sensors. Each channel provides complete channel-to-channel isolation, preventing ground potential differences and line-noise crosstalk between ungrounded or grounded sensor loops. The module interfaces directly with the local rack backplane system for power distribution, diagnostic parsing, and real-time sampling without requiring external isolation transmitters.

Hardware Specifications

ControlLogix System Architecture & Backplane Protocol Features

The module communicates over the local ControlLogix backplane bus utilizing high-velocity CIP (Common Industrial Protocol) framing. Backplane bus communication velocity guarantees low deterministic latency during real-time RTD channel sampling and data multicasting. High-density I/O routing protocols allow configuring Real-Time Sampling (RTS) and Requested Packet Interval (RPI) periods down to minimal scan thresholds. Firmware flash compatibility enables online channel reconfiguration, filter adjustments, and firmware synchronization via Studio 5000 Logix Designer software without interrupting backplane power.

Frequently Asked Questions

Q: Can the 1756-IR6I module be removed or inserted under power (RIUP)?

A: Yes, the 1756-IR6I supports Removal and Insertion Under Power (RIUP) within a powered ControlLogix chassis. However, field wiring connected to the 20-pin Removable Terminal Block (RTB) should be safely disconnected or isolated to prevent signal transients during module insertion.

Q: What data formats are selectable for processing thermal readings on the 1756-IR6I?

A: The module supports Integer mode (left-justified 2s complement) and IEEE 32-bit floating-point mode. Floating-point mode enables integrated temperature linearization (Celsius or Fahrenheit), process/rate alarms, and digital filtering algorithms directly on the module.

Field Installation Guidelines

• Verify backplane chassis grounding satisfies IEEE 1100 standards; connect the chassis ground lug to the enclosure single-point star ground using low-impedance copper wire.
• Secure the 1756-TBNH or 1756-TBSH Removable Terminal Block (RTB) retaining screws to ensure proper mechanical seating against chassis alignment keyways.
• Route RTD sensor lead wiring in dedicated low-voltage instrument raceways, maintaining separation from AC power lines and drive output cables to minimize inductive interference.
• Connect RTD cable shields at a single ground termination point (typically at the cabinet panel enclosure) to prevent ground loops across isolated input channels.