ch = 1, 2 or 3 (COMM port number)

ch, mode =

0 - Auto sensing (default mode)
1 - Fixed at RTU mode
2 - Fixed at EMIT mode
3 - Fixed at MODBUS ASCII mode
4 - Fixed at OMRON C20H protocol mode
5 - Fixed at NATIVE host link command mode
10- No protocol. (For creating user own custom protocol.

IMPORTANT:

1. Please note that if you set the protocol to other than the "Native" (mode=5) or "Auto" (mode=0) that serial port will no longer respond to commands from i-TRiLOGI and you will encounter "Communication Errors" when you try to perform any communication using i-TRiLOGI with that serial port. You can still use the other unaffected serial port (e.g. COMM3, RS485) that support host link commands.
   
2. For all Nano-10, FMD series, and F-series PLC (as well as the legacy T100M series PLCs with firmware revision r42 or above), setting the protocol mode to NATIVE (mode=5) disables support for point-to-point communication. Also, the wildcard FCS (i.e. 00) is not allowed in multi-point format in this mode. This is to ensure the maximum data integrity by accepting only commands that are fully formatted with correct FCS error check. Note that this means i-TRiLOGI's "Detect ID" function will not work since the PLC with protocol mode =5 will not respond to point-to-point protocol "IR*". You will have to manually enter the ID into i-TRiLOGI login dialog box to communicate with the PLC.
   
3. To regain communication with the serial port that has been changed by SETPROTOCOL command, you will have to execute another SETPROTOCOL function that set it to mode 0 or 5 (assuming it has been written into the program), or you must reset the controller by turning OFF the power and then ON again. If you execute a SETPROTOCOL using the 1ST.Scan then you must turn on DIP switch #4 before powering up the PLC so that the SETPROTOCOL command will not be executed and you can regain control of the PLC using i-TRiLOGI.