Modbus poll error

4:01:52 PM ReadDiscreteInputsRequest Received response with ExceptionCode: 0x04 (SlaveDeviceFailure).
(T) 4:01:52 PM ReadDiscreteInputsRequest Received message: [ 44 D5 00 00 00 03 02 82 04 ]
(T) 4:01:52 PM ReadDiscreteInputsRequest Sending message: [ 44 D5 00 00 00 06 02 02 5C AE 00 01 ]

See above.

This is the MODBUS TCP protocol. I have interperted the requested register as 23726. What my problem is, I cannot find anything addressed within the Ignition project to this register.

In my PLC system, this address is not used. It is definitely invalid, but I cannot find what is driving it. It is on a 1 second scan.

I have been away from Ignition for a while and am a bit rusty.

Any input would be appeciated

So your tags can be defined in two places depending on personal choice. First is in gateway. You can use the address mapping tool accessed from the gateway devices page to define groups of tags starting at a specific modbus address. So it’s possible that you defined that in there somewhere and then dragged that tag into the designer making it part of a one second scanclass.

The other way you could have defined that tag was manually creating a tag in the designer. In this case you would have a tag addressed something like the following:


I have a feeling you likely addressed it in the gateway seeing that you can’t find a reference to that address anywhere in the project.