Siemens s7-1500 tags turn green after adding data

I was running into problems where I would add some tags (6 of them) and I would add a seventh tag and all of my tags would get a little green symbol.

I would then delete the six tags I previously added and re-add the seventh tag, and it would be fine.


It turned out to be an issue with the Siemens driver (v3.8.3) in which IA is currently working to resolve.

I fixed my problem by monitoring less data (I had a few large 256 byte strings that I stopped looking at).

String Path: ns=1;s=[PLC_Siemens]DB5500,string52.5
.5 limits the length to 5 bytes.

I encountered the same problem with Siemens S7-414 CPU earlier this year…

It turns out that IA Siemens driver can’t read STRINGs from Siemens PLC longer than 202 bytes.