Posted 13 Sep 2021 Has anyone used the Modbus RTU for SCU function block from Omron France at all? I have written a heap of code and getting done bits back and moving on to the next read fine but there is no data coming back. I have uploaded the function block here as well. I have not uploaded the code at the moment - there is a hell of a lot of it. The processor is a CJ2M-CPU35 - big boy. Ran out of memory with a lesser processor. May have to go back to the PMCR system if no one can help. MRTU_SCU_Master.zip Share this post Link to post Share on other sites
Posted 13 Sep 2021 Here is a section of the program I have written. The done bit is used as a differentiated contact to operate the step flag. That all works but no data coming back at all. No errors either. hopefully someone can help. I do not often get stuck over a problem - stuck this time. Modbus RTU Problem.cxp Share this post Link to post Share on other sites
Posted 15 Sep 2021 Hi Bob, You are calling 40 instances of the FB each scan. The limit for this block is 32. Have you tried to run just a single instance to see if you get a reply? Share this post Link to post Share on other sites
Posted 15 Sep 2021 (edited) Hi Chelton - will give it a go - I did not think the quantity would matter as I am using the done bit but nothing is coming back so do not know why the done bit is turning on. This lot is power monitors - I have another lot for AOP sterilisers and another lot for VSDs. All on their own serial ports but there are quite a few reads from the drives as well. I just put a set bit in and then a .2 timer in front of the read bit and the timer also reset the bit. Slowed things down - no result either. Puzzled. Back to PMCR I think. Edited 15 Sep 2021 by BobB Share this post Link to post Share on other sites
Posted 15 Sep 2021 Did you set up your SCU as per the documentation? Share this post Link to post Share on other sites
Posted 15 Sep 2021 Did not set the timeout - everything else is correct. Did not think timeout would matter - will give it a go. Otherwise back to PMCR - pressure on of course and no time to fiddle. Thanks for looking and helping. Share this post Link to post Share on other sites
Posted 15 Sep 2021 Time out addition did not help - still no response. Back to PMCR - have to get it done. Share this post Link to post Share on other sites