Product Overview
The Allen-Bradley 1771-IB is a digital DC input module designed for the PLC-5 family of programmable logic controllers. It converts DC signals from field devices into the logic levels required by the processor, updating the corresponding bits in the PLC data table. This module offers a compact, modular way to expand input capacity without excessive wiring or panel space.
With 8 isolated input channels and a voltage category of 10–60V DC (sink/source load), the 1771-IB suits a wide range of industrial sensing and switching applications. Its operating voltage range of 10–27V DC ensures compatibility with common 12V and 24V control systems. The module features opto-electrical isolation and input filtering to protect against electrical transients and reduce noise, enhancing system reliability.
Technical Specifications
Below are the key specifications for the Allen-Bradley 1771-IB module, sourced directly from the manufacturer's data.
| Parameter |
Value |
| Manufacturer |
Rockwell Automation |
| Brand |
Allen-Bradley |
| Part Number / Catalog No. |
1771-IB |
| Module Type |
Digital DC Input Module |
| Number of Inputs |
8 Inputs |
| Voltage Category |
10-60 Volts DC, Sink (Source Load) |
| DC Operating Voltage |
10-27 Volts |
| Backplane Current |
74 Milliamperes |
| Max DC Off-State Current |
3.0 Milliamperes |
| Typical DC Signal Delay (On) |
N/A |
| Typical DC Signal Delay (Off) |
N/A |
| Wiring Arm |
1771-WN |
| Typical AC Signal Delay (Off) |
20 (+/- 15) ms |
| Dimensions |
3.5 x 6.5 x 2.0 in (89 x 165 x 51 mm) |
The 1771-IB draws a backplane current of 74 mA and has a maximum off-state current of 3.0 mA, ensuring low power consumption and minimal leakage. Its compact dimensions make it easy to fit into existing 1771 I/O chassis.
Installation & Setup Guidance
Installing the 1771-IB is straightforward. Ensure the module is inserted into a compatible 1771 I/O chassis with a PLC-5 processor. Keying bands are located between pins 14 and 16 on the upper connector and between pins 4 and 6 on the lower connector to prevent incorrect insertion. Use the 1771-WN wiring arm for field wiring; this allows module replacement without disconnecting the wiring. Always power down the system before removing or inserting the module to avoid damage.
Maintenance & Reliability
The 1771-IB requires minimal maintenance. Periodically check the front panel status indicators (8 red LEDs) to confirm proper field-side operation. Keep the module free of dust and moisture, and ensure adequate airflow around the chassis to prevent overheating. The module's opto-electrical isolation protects internal circuits from transients, reducing the risk of failure. With proper care, this module provides long service life, minimizing downtime and replacement costs.
Compatibility & Integration
The 1771-IB is part of the Allen-Bradley PLC-5 family and is compatible with 1771 I/O chassis and PLC-5 processors. It supports ½, 1, and 2-slot I/O addressing. The module works with source-switching devices such as dry-contact switches, electro-mechanical transmitters, selector switches, and pushbuttons. It is a Series A module, ensuring broad compatibility with existing PLC-5 systems.
Selection Guide & Purchasing Advice
Before purchasing the 1771-IB, verify that your PLC-5 chassis has an available slot and that the power supply can handle the additional backplane current (74 mA). Confirm the wiring arm model (1771-WN) is included or order it separately. The module is suitable for applications requiring reliable DC input sensing. PLC Source PRO offers genuine Allen-Bradley parts with fast shipping, ensuring you get the right component for your system.