尝试以下将对您有用
serialPort1.Write("Test message from coded program" + (char)26);
Run Code Online (Sandbox Code Playgroud)
也尝试可能对你有用
serialPort1.Write("Test message from coded program");
SendKeys.Send("^(z)");
Run Code Online (Sandbox Code Playgroud)
另请检查:http ://www.dreamincode.net/forums/topic/48708-sending-ctrl-z-through-serial/