rwraley Posted November 30, 2007 Report Posted November 30, 2007 Hi all, I am not well versed in Modicon gear and have been trying to figure out an issue in which the Modicon 984 is talking to a UniOp EL25T operator interface over the MB1 port. It apparently worked fine for many years then the communications started to get intermittent and now are non existent. So you can not read or write to the registers from the HMI. I do not have the software for the HMI but can go online with the Modicon what are some things I can look for in the plc program that might clue me in? Is the MB1 port modbus over an RS-232 connection (RJ45{plc} to 15 pin D shell{HMI}).Any advice is greatly appreciated since I know zip of Modicon plc's. Thanks. Quote
Crossbow Posted December 2, 2007 Report Posted December 2, 2007 It is an RS232 port using the RJ45 plug. I doubt there is anything in the PLC program you can find to explain this. I would sooner look at the port or the cable being damaged. PLCs which have been programmed and working for years don't just change on their own. Quote
rwraley Posted December 3, 2007 Author Report Posted December 3, 2007 It ended being a bad (intermittent) com port on the CPU. Thanks for the response. Quote
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