Rockwell Automation 1747-L5xx SLC 500 Modular Hardware Style User Manual - Manual (Page 163)

Publication 1747-UM011G-EN-P - June 2008
Troubleshooting 163
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
Isolation
Logic
Circuits
Backplane
status indicator