Extron Electronics MVC 121 - Manual (Page 28)

MVC 121• Remote Control
Remote Control
3-2
RS-232 Programmer’s Guide
The MVC 121 can be remotely controlled via a host
computer attached to the rear panel’s 3-pole captive
screw RS-232 connector. The protocol is 9600 baud,
1 stop bit, no parity, and no flow control.
The RS-232 control device (host) can use either Extron’s Simple
Instruction Set (SIS) commands or the graphical control
program for Windows. Windows control software is included
with the MVC.
The rear panel’s RS-232 3-pole female connector has the
following pin assignments:
Pin RS-232 function Description
1 Tx Transmit data
2 Rx Receive data
3 Gnd Signal ground
Host-to-MVC communications
SIS commands consist of one or more characters per field. No
special characters are required to begin or end a command
sequence. When a command is valid, the MVC executes the
command and sends a response to the host device. All
responses from the MVC to the host end with a carriage return
and a line feed (CR/LF =
), which signals the end of the
response character string. A string is one or more characters.
MVC-initiated messages
When a local event such as a front panel or contact closure
selection or adjustment takes place, the MVC sends a message
to the host. No response is required from the host. One MVC-
initiated message is listed here (underlined).
(C) Copyright 2004, Extron Electronics, MVC 121, V x.xx
The MVC issues the copyright message when it first powers on.
V x.xx is the firmware version number.
Other examples of unsolicited responses are indicated in the SIS
command/response table by a following every description of
a response that could also be an unsolicited response.
Error responses
When the MVC 121 receives a valid SIS command, it executes
the command and sends a response to the host device. If the
MVC is unable to execute the command because the command
RS-232
Tx Rx