Product Overview
The Allen-Bradley 1771-IG is a digital DC input module from the PLC-5 series by Rockwell Automation. Designed for maintenance engineers, this module converts TTL-level DC signals from user devices into logic levels for the processor, updating corresponding bits in the PLC data table. It requires two power sources: the I/O chassis backplane and an user-supplied 5 Volts DC supply for TTL signal transmission. The module is not designed for AC voltage operation, ensuring safe integration in DC-only environments.
Technical Specifications Breakdown
Key parameters for the 1771-IG are listed below for quick reference:
| Feature | Specification |
|---|---|
| Manufacturer | Rockwell Automation |
| Brand | Allen-Bradley |
| Part Number | 1771-IG |
| Module Type | Digital DC Input Module |
| Number of Inputs | 8 Inputs |
| Voltage Category | 5 Volts DC, TTL |
| DC Operating Voltage | 5.0-5.3 Volts |
| Backplane Current | 122 Miliamperes |
| Typical DC Signal Delay (On) | < 1 ms |
| Typical DC Signal Delay (Off) | 20 (+/- 9) ms |
| Wiring Arm | 1771-WC |
| Coating | Conformal Coat |
| Mounting | Rack Mountable |
Industry Applications
In packaging lines, it reads encoder signals for precise position control, reducing downtime due to signal noise. In automated assembly, its 8 inputs handle multiple sensor states, while the conformal coating protects against moisture and dust in harsh factory floors. The optoelectrical isolation shields the PLC processor from transients, enhancing system longevity.
Installation & Setup Guidance
Mount the 1771-IG in a 1771 I/O chassis with a PLC processor. Keying bands between pins 34 and 36 (upper connector) and pins 4 and 6 (lower connector) ensure correct slot placement. Connect an user-supplied 5V DC power source for TTL signal transmission; the backplane provides 122mA current. Verify the DC operating voltage stays within 5.0-5.3V to avoid input damage. The module supports ½, 1, and 2-slot I/O addressing for flexible configuration.
Maintenance & Reliability
Inspect the front panel status indicators regularly to verify TTL voltage sensing. The conformal coating enhances resistance to humidity and contaminants, reducing failure rates in demanding environments. The input filtering feature minimizes electrical noise, improving signal integrity. No disassembly is required for routine checks; simply monitor the eight indicators and ensure the 5V DC supply remains stable. For long-term reliability, keep the chassis clean and verify backplane connections annually.
Compatibility & Integration
It is a Series A module, compatible with standard PLC-5 addressing schemes. The TTL input design makes it suitable for interfacing with BCD encoders and other TTL-level devices. For replacement or expansion, verify compatibility with your existing PLC-5 system and power supply ratings.
Selection Guide & Purchasing Advice
When selecting the 1771-IG, confirm your application requires 5V DC TTL inputs with 8 channels. AutoDCSTech offers this module with fast shipping and expert support. Please verify current lifecycle status and availability with AutoDCSTech before ordering, as this module may be nearing obsolescence.
Troubleshooting & Common Issues
If inputs fail to register, check the user-supplied 5V DC power source and ensure voltage is within 5.0-5.3V. Verify that the 1771-WC wiring arm is fully seated and connections are secure. If signal delays seem excessive, note that off-delay is typically 20 (+/- 9) ms; if outside this range, inspect for noise or wiring faults. The eight status indicators help isolate faulty channels. For persistent issues, replace the module using the wiring arm without rewiring.
Availability & Condition at AutoDCSTech
| Part Number | 1771-IG |
|---|---|
| Availability | In Stock |
| Condition | New |
| Warranty | One Year |
| Origin | US |
