Current/Load Calculation for S800I/O - AO Card goes to error in a redundant configuration
How the load calculation for S800 redundancy I/O is done ?
We have cluster with 6 redundancy set of AO card (AO845) , fully AO cluster - but always one Card goes to error mode in the redundant set.
- we are facing issue with one cluster , where we have 6 redundancy AO card 75% channel is utilized.
- some of the cable length is 550 meter with 1mm2 cable
- When plant is shutdown and remove/reset the card the I/O error is disappears , as soon as the plant start then the AO output will be close to 20mA the cards goes to fault again.
According to the manuals, 12 modules AO845 in one cluster (or 6 redundant pairs) should not exceed the power supply limits.
In your case it is 12*125mA = 1,5A from 5VDC of modulebus.
External 24VDC required for the modules is 12*165mA = 1,98A including load current (check your external 24VDC power supply module)
Look in table 24 in 3BSE020923-600A for example
I think you have to look for the problem not in configuration, but somewhere outside, if the cluster is working fine at idle state.
Unfortunately you have provided too limited information - what is the error code/description, what is your cluster configuration/cluster modem, is the problem all the tie in the same module, or in random modules from the cluster?