Extron Electronics USP 405 User Guide - Manual (Page 42)

USP 405 • Serial Communication 3-2
Serial Communication
The USP 405 can be remotely controlled via a host computer or other device
(such as a control system) attached to the rear panel RS-232 connector. The
control device (host) can use either Extron’s Simple Instruction Set (SIS)
commands or the graphical control program for Windows.
The signal processor uses a protocol of 9600 baud, 1 stop bit, no parity, and no
flow control.
The rear panel RS-232, 9-pin D connector has the following pin assignments:
Pin RS-232 function Description
Contact closure Input 1 1
Transmit data Tx 2
No connection – 9
Contact closure Input 5 8
Contact closure Input 4 7
Contact closure Input 3 6
Signal ground Gnd 5
Contact closure Input 2 4
Receive data Rx 3
RS-232 Programmer’s Guide
Host-to-signal processor communications
SIS commands consist of one or more characters per field. No special characters
are required to begin or end a command sequence. When the USP 405
determines that a command is valid, it executes the command and sends a
response to the host device. All responses from the signal processor 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.
It is also possible to send several SIS commands back-to-back in sequence.
Signal processor-initiated messages
When a local event such as a front panel selection or adjustment takes place, the
USP 405 signal processor responds by sending a message to the host. No
response is required from the host. The signal processor-initiated messages are
listed here (underlined).
(C) Copyright 2002, Extron Electronics, USP 405, Vx.xx
The USP 405 sends the copyright message when it first powers on. Vx.xx is the
firmware version number.
C hn
X1
(where
X1
is the input number)
The USP 405 sends this response when an input is switched.
Error responses
When the USP 405 receives a valid SIS command, it executes the command and
sends a response to the host device. If the USP is unable to execute the command
because the command is invalid or it contains invalid parameters, it returns an
error response to the host.
The error response codes and their descriptions are as follows:
E01 – Invalid input channel number (the number is too large)
E10 – Invalid command
E11 – Invalid preset value
E13 – Invalid value (the number is out of range/too large)
E17 – Illegal command for this signal type
DB9 Pin Locations
Female
5 1
9 6