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I'm using the SMS OPOS drivers for my pole display, and there are invalid or garbage characters showing up on the line display.
The OPOS line display driver relies on the operating system to initialize the serial communication port. It does not initialize the port and program the baud rate, start/stop bits, and parity. On some installations, the operating system does not always initialize the communication port on power-up. So the port is left at an unknown state, thus causing the data to be misinterpreted.
To verify this is the cause, use the DOS mode command to initialize the port with the same communication parameters specified in the OPOS driver and re-run the POS program. If this fix the problem, you may want to add the Mode command in the AUTOEXEC.BAT file so it can be automatically executed every time the computer is started. For example:
MODE COM1: 9600,n,8,2
This work around solution has been tested with the Logic Controls PD2000 and PD3000 line displays.