Troubleshooting Your Input Modules; Input Circuit Operation - Allen-Bradley SLC 500 User Manual

Troubleshooting Your Input
Modules
The following will assist you in troubleshooting your input modules.

Input Circuit Operation

An input circuit responds to an input signal in the following manner.
1. An input filter removes false signals due to contact bounce or
electrical interference.
2. Opto-electrical isolation protects the input circuit and backplane
circuits by isolating logic circuits from input signals.
3. Logic circuits process the signal.
4. An input status indicator turns on or off indicating the status of
the corresponding input device.
Input
Input
Conditioning
Opto-Electrical Logic
Isolation Circuits
Publication 1747-UM011G-EN-P - June 2008
Troubleshooting
163
Backplane
status indicator