The Allen-Bradley 1756-IA32, also cataloged as the 1756IA32 Discrete Input Module, operates as a dedicated hardware component for 120 VAC discrete signal acquisition and state sensing within ControlLogix chassis backplane environments.

Part Number Breakdown & Identification

• 1756: Chassis-based ControlLogix I/O system hardware architecture platform.
• IA32: 120 VAC nominal input voltage rating configured with 32 high-density discrete input channels.
• 1756IA32: Service spare part number variant corresponding to the standard 1756-IA32 assembly.

Technical Performance Parameters

EtherNet/IP Networks & System Architecture

The module utilizes high-density I/O density scaling across the local backplane, transmitting channel states to ControlLogix PAC controllers over EtherNet/IP deterministic networks. Embedded hardware logic provides selectable programmable filter delays of 9 ms or 18 ms to suppress contact bounce. Module keying and software-defined electronic keying prevent physical insertion errors into incorrect backplane slots, preserving firmware flash compatibility across active controller projects.

Delivery Package Details

• 1 x Allen-Bradley 1756-IA32 ControlLogix Module Unit

Wiring Protocol & Slot Assembly Guidelines

Chassis Insertion & Keying

• Configure slot electronic keying parameters in Logix Designer before inserting the card into the 1756 backplane.
• Align the circuit board with the top and bottom chassis card guides, pushing firmly until the top and bottom retaining tabs latch cleanly.

Field Wiring & Cable Separation

• Connect 120 VAC field wiring via a 36-pin or 20-pin Removable Terminal Block (RTB) or IFM pre-wired cable system.
• Maintain strict physical separation between 120 VAC discrete input conductors and low-level analog or communication bus cabling to prevent inductive crosstalk.

Frequently Asked Questions

• What is the nominal operating voltage range for the 1756-IA32 inputs?

  The input channels accept AC operating signals ranging from 74 VAC minimum up to 132 VAC maximum at 50/60 Hz frequencies.

• What current does the module draw from the 5 VDC backplane bus?

  The card draws a continuous current load of 165 mA from the 5 VDC chassis backplane rail during standard operation.

• What digital input filtering options can be configured on this module?

  Engineers can select programmable digital input filter times of either 9 ms or 18 ms to accommodate field contact settling times.

• What is the maximum allowable off-state leakage current?

  Field devices must maintain an off-state leakage current below 2.5 mA to ensure the channel detects a valid logic OFF condition.

• How much power does the module dissipate under maximum operating thermal load?

  The module dissipates a maximum of 6.1 W at 60 deg C, equivalent to a thermal dissipation rate of 20.8 BTU/hr.

• Are the 32 input channels isolated from one another?

  The 32 input channels are arranged in 4 isolated groups of 8 channels each, sharing common neutral return points per group.

• What hardware propagation delays apply to state transitions?

  OFF-to-ON hardware delay is 1.5 ms nominal (10 ms max) plus filter time; ON-to-OFF is 1.0 ms nominal (8 ms max) plus filter time.

• Does the 1756-IA32 support Removal and Insertion Under Power (RIUP)?

  Yes, ControlLogix modules support RIUP, allowing module replacement while backplane power is applied if the area is non-hazardous.