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Wiser for KNX and modbus problem
Ideas anyone? It seems almost that the slave 8 (but 9 is the same) respond as slave 130...I see a sort of pattern here since slave 8 and 9 are two PM3250, but I can't find any sense in that behavior...
The communication errors are caused by cabling, topology and/or noise sources that affect the signal quality. Another possibility is a damaged RS-485 chip on one of the devices. If real-time data acquisition is not needed then some errors during communication are acceptable.
Topology is correct (we even undo that short branch), cabling I assume it's the same since we use certified cables, could be some noise but with twisted pairs, terminating resistors and signal grounds I don't see how.

Thanks for help anyway, I think that it's the best that we can provide in this situation.
Two weeks ago I was helping in one installation. 16 slaves where two were the PM3255 you have. Everything just worked but the cabling was spot on. If you are confident about cables I would disconnect all slaves and try them one by one.

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