Writing to Tag Array Element

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1

Hi All

I'm working with a PLC that has an DINT array, I can read the individual elements but I can't seem to change the value in an array member?

On the PLC, it's a array of 32 bool values and it seems to be mapped correctly in persepctive

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If I try and change it via the tag browser or via a button I get the following error:

Error writing to HMI_Cmds_0_[0]: Error_Exception: Error writing to tag '[PLC]HMI Status/HMI_Cmds/HMI_Cmds_0_': null

My OPC Path is

ns=1;s=[PLC]HMI_Cmds[0]

I've tried an array of INT and BOOL with similar effects. Is there any suggestions what the best way to do this is? The aim here is to be able to toggle these bool's which leads down to function on the PLC

S

2

Don't use an array. Make individual bit tags that point at the PLC addresses. Writes to individual boolean tags can be properly handled by the driver to make the correct PLC writes.

3

Thanks. I'm not sure how best to make a and individual tag? When adding a tag it doesn't give me the breakdown of the "value" item in the array? or do you mean on the PLC, convert them to an individual tag?

4

You can manually add a dot and the bit number to the OPC Item Path of the word containing the bit. Drag n drop doesn't cover all possible syntax.

5

Thanks. I was able to get it to work. Just the suffix as below. Thanks for your help as always

ns=1;s=[PLC]HMI_Cmds[0].0