Here I want to control a relay board with COM port(RS 232), its switch on command is "01 05 00 00 FF 00 8C 3A",
At the beginning, I use a COM debug application(XCOM V2.0) to try the connection, and it is working properly.
see below picture,
Then I try to use the "Direct I/O" to control the relay board, the problem is no response!
please see below picture, and I double checked the serial port setting, it is correct.
how should I do next step? thanks a lot!
BTW, both "EOL OFF" and "EOL ON" were tried, but didn't work.