Hi, you can use a mini to monitor relay operation, but how you do it will depend on the type of relays.
- Coil Voltage, AC or DC
- If relay has extra set of unused contacts that can be used to monitor condition
If each relay has a set of unused contacts you can use those as input to the mini to directly indicate if relay ON or OFF, it will also show relay mechanical failure.
If not, then monitor the coil voltage using opto couplers.
Tom..... 