AVocation Systems MX-0404NAD/R - Manual (Page 9)

C11
Section C - Control Connections
The MTX series of matrices can be controlled via RS-232, RS-485 and infrared.
RS-232 Connections to the matrix typically use a null modem cable from the controller.
The default communications parameters are:
Receive (Pin 2)
Transmit (Pin 3)
Ground (Pin 5)
Data- (Pin 3)
Data+ (Pin 4)
Infrared
Teaching
Output
Baud Rate 19200 baud
Bits 8
Parity None
Stop Bits 1
RS-485 communications use the same baud rate as RS-232. Both RJ-12 connectors are tied together to allow daisy
chained communications.