KarvaneSiil Posted April 19, 2022 Report Share Posted April 19, 2022 Hello, PLC: USP-104-B10 UniLogic 1.23.25 I am relatively now to Unitronics but have experience with PLCs and programming and things. So this is like weird thing happening. I have 3 Kamstrup heat meters - PLC reads with Aperiodic Trigger block every second, 38400baud, so there should be enough time for communication I think, response timeout is set 500ms. The communication fail rate is 4% for some reason - but OK, I can live with that. But what I notice is that the Session skips sometimes. Usually it goes device 1->2->3->1->2->3 and sometimes 1->2->3->...->2->3 and that's when weird things start to happen - heat meters DATA switches places between each other!? Then after a 2 or 3 correct round of readings everything goes back to correct places. How can communication send out read request to node 170 and then when back comes data from node 171 it decides that this is the correct message I was looking for? Now things get even worse when I add Multimeter and VFD device into communication. After program download everything works fine for a about 20-30 minutes, and after that it just fails. 80% messages fail, skipping sessions, random successful messages, DATA switches places. I replaced communication modules on heat meters, comm module on PLC. We have same type of devices working on other sites and no problem, but this project is a headache. Any suggestions? Quote Link to comment Share on other sites More sharing options...
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