After a planned power outage due to a 24volt transformer failure Friday 10/15 the FMCS system failed to communicate with the DMS 3500 units. Vendor Control Solutions Northwest arrived Thursday 10/21 am to look at the problem. The issue turned out to be a mismatch in serial port configuration at the 3500 unit. The default setting is apparently incorrect when used to communicate with the UNC 500 which we have.
The correct serial port config at the 3500 is: 38.4,1,7,E,M,N. (in the non functioning state is was found to be 38.4,1,7,E,P,N)
Note that this only applies to the port which is connected to the UNC.