Here at our station, they recently had to replace a bad S1 controller with a new S1. Now, one single Bristol RTU (serial communication) won’t talk to it. There are 3 RTU’s and the other 2 still work. As far as I know, no changes were made to the programming. It accesses a subroutine called “MBMaster Read Holding RegistersTW”.
The subroutine is a Modbus serial V1.1 program from 2007. It successfully opens a session with the RTU, but when it gets to the transmit and receive portion it delays out and never receives data. Any idea where I can look or what I can check? We verified the RTU is working for other communication to our SCADA network, but it won’t talk to Opto!!