AMX NetLinx NXM Series - Manual (Page 19)

NXC-COM2 Dual COM Port Control Card
13 NetLinx Cardframe, Control Cards, and NetModules
NXC-COM2 Send_String Escape Sequences (Cont.)
Command Description
27,20,1
Set the RTS hardware
handshake's output to
low/inactive (< 3V). Syntax:
SEND_STRING <DEV>,"27,20,1"
Example:
SEND_STRING RS232_1,"27,20,1"
Sets the RTS hardware handshake's output to low on the RS232_1
device.