Description
The 1756-IA32 is a 32-point AC digital input module manufactured by Rockwell Automation under the Allen-Bradley brand for the ControlLogix 1756 platform. It monitors 74–132V AC field signals and transmits their on/off status to the ControlLogix processor through the chassis backplane.
The 1756-IA32 converts real-world AC device states into digital control data without requiring an external input card power supply. Its high-density design allows one module to monitor 32 field devices while occupying a single ControlLogix chassis slot.
Application Scenarios
A bottling plant needed to monitor numerous 120V AC signals from conveyor interlocks, selector switches, auxiliary relay contacts, valve-position indicators, and machine-status contacts. Using low-density input modules would have consumed additional chassis slots and increased terminal-block quantity, panel wiring, and documentation complexity.
The engineering team installed the 1756-IA32 to consolidate these signals. Each AC input represented one device state in the ControlLogix program, while front-panel indicators helped technicians confirm signal presence during commissioning and troubleshooting. The plant reduced the number of required I/O modules and maintained a clear relationship between physical wiring and controller tags.
This type of application shows why the 1756-IA32 remains valuable: it is not only the 32 input points that matter, but also the combination of high density, AC voltage compatibility, and straightforward integration with a ControlLogix processor and human-machine interface.
Parameter
| Main Parameters | Value/Description |
|---|---|
| Product Model | 1756-IA32 |
| Manufacturer | Rockwell Automation |
| Brand | Allen-Bradley |
| Product Category | ControlLogix AC digital input module |
| Number of Inputs | 32 |
| Input Grouping | 4 groups of 8 inputs |
| Nominal Input Voltage | 120V AC |
| Operating Voltage Range | 74–132V AC |
| Input Frequency | 47–63 Hz |
| On-State Current | 5 mA minimum at 74V AC; 15 mA maximum at 132V AC |
| Off-State Voltage | 20V maximum |
| Off-State Current | 2.5 mA maximum |
| Input Impedance | 14.0 kΩ maximum at 132V AC, 60 Hz |
| Maximum Inrush Current | 390 mA |
| OFF-to-ON Delay | 1.5 ms nominal / 10 ms maximum plus selected filter time |
| ON-to-OFF Delay | 1 ms nominal / 8 ms maximum plus selected filter time |
| Selectable Filter Time | OFF-to-ON: 1 or 2 ms; ON-to-OFF: 9 or 18 ms |
| Cyclic Update Time | 200 μs to 750 ms |
| Change-of-State Timestamp | ±200 μs |
| Isolation Voltage | 250V continuous from inputs to backplane |
| Group Isolation | 125V continuous between input groups |
| Backplane Current | 165 mA at 5.1V DC; 2 mA at 24V DC |
| Power Dissipation | 6.1 W maximum at 60 °C |
| Terminal Block Housing | 1756-TBCH or 1756-TBS6H |
| Chassis Slots Required | 1 |
| Operating Temperature | 0…60 °C (32…140 °F) |
| Humidity | 5…95% noncondensing |
