If your system had four such inputs, then the wiring diagram would again show an array of input devices displayed in ladder fashion. But this time, they wouldn’t share L1. Instead, each would be ...

The Click C0-04TRS-10 ($54.00) is a 4-point, 10A per point, isolated relay output module with four Form A (SPST) relays and 4 isolated commons. Operating voltage range is 6-24 VDC / 6-240 VAC. The ...

If they do, the problem is on the processor side of the input module. Next, watch the PLC logic for a corresponding change. If it doesn't happen, then the signal isn't making it from the input module ...