Hi y'all: I've been using M-91 PLCs successfully in various applications and only recently came across a customer supplied M91-2-T1 that does not seem to be able to establish communication to program via the RS232 port.  The PLC powers up fine as I see the old legacy program running on the hardware; however, whenever I try to download some test ladder logic, or even pull some PLC data, I get the "Communication could not be established" error message. Things that I've tested: 1) Th