Protocol Commands Protocol Command (Mnemonic displayed on menu) Control Characters (Entered in menu or serial command) Hex Value Effect of Command RES ^D 04 Reset REQ ^E 05 Request EOT ^D 04 Reset STX ^B 02 Start of Text ETX ^C 03 End of Text ACK ^F 06 Acknowledge NAK ^U 15 Negative Acknowledge XON ^Q 11 Begin Transmission XOFF ^S 13 Stop Transmission