Error writing to I:0_0_05.value on A-B MicroLogix 1100

When I try to assign 1 to tag I:0_0_05 I get this :
Error writing to I:0_0_05.value:
Bad("Bad_NotWritable:The access level does not allow writing to the Node.")
The HMI buttom works because I can print something in the output console also I don't have this issue when I replace the input tag with an output tag .
I have ignition 8.1 and a Micrologix 1100.

That tag looks like it's for a physical input, so writing to it would be considered forcing it on or off, and I don't normally see these forced from an HMI write because the PLC would just undo it during the next scan if the hard wired input wasn't present. I believe the common practice is to set up an input map that sets a binary tag, and the binary tag does all of the work of the input in the program. A second binary tag that does not have a destructive bit in the PLC program can then be written to from an HMI for purposes of interrupting or bypassing the input as needed. It's the same effect, but it's considered toggling since its not overriding a physical condition such as a sink/source input.



I second the recommendation to use pseudo IO. If you use the physical I/O tag, or even an alias, and you need to change one of them for whatever reason, you'll need to download to the PLC since those tags cannot be changed while online.

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Thanks Justin and Ryan for the replies and that was a great graphical explanation. Also from the online docs : " The micrologix driver cannot access Input parameters" I guess this is the reason why I cannot modify the input from the HMI.