Fernando Castro Posted July 6, 2022 Report Share Posted July 6, 2022 Just to put all of you in context, I have a network of 180 Unitronics PLCs between v570 and v700. eventually, every PLC will have the "same" software (I am managing 2 versions of software one for each model) There is a "server" (PC) that works as a Modbus master, and all the PLCs are Modbus slaves, the "server" continuously pulls data from the slaves At the same time, there are other extra ports on the PLCs enabled for the Unitronics Suite (Remote operator, sd card explorer, download manager). All the PLCs IP are static and manually managed. every Software compiled for the download has the same OS, so that has been standardized as well. So far everything has been working fine but then ... I have this issue with just 1 device that randomly stops responding to Modbus Master. First I thought maybe another device was connected on the same network with DHCP enabled and was stealing that IP but I can connect using a remote operator. so that rules out both IP settings and faulty cables. I already tried to swap the physical "socket" connection just to rule out any configurations on the managed switch. I already tried to use a different IP to test if by any chance the other machine happens to be a Modbus master using the same port and is trying to establish a connection to that specific IP (very unlikely In my opinion). But in both cases still, the same PLC eventually stopped responding to my Modbus master. The funny thing is that I can restore the connection using the refresh button that I programmed on the PLC which closes the socket, restarts it, and run the Modbus config once again to restart the communication. The only clue I have so far is that the error that the server shows is different from the one that I get from a disconnected device, disconnected devices eventually trigger timeout on requests. for this device, I get "unable to read". Any Ideas? I hate to say it because to me it always sounded like a lazy troubleshooting when I hear it but... I think maybe there is a problem with the PLC?? Quote Link to comment Share on other sites More sharing options...
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