Serial Communication

The DVS 304 can be remotely controlled via a host computer or other device (such as a control system) attached to the rear panel RS-232 connector or the LAN port. The control device (host) can use either Extron’s Simple Instruction Set (SIS™) commands or the graphical control program for Windows.

The scaler 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
1	Input #1	Contact closure	5	1
2	Tx	Transmit data
3	Rx	Receive data
4	Input #2	Contact closure	9	6
5	Gnd	Signal ground	9	6
5	Gnd	Signal ground	DB9 Pin Locations
6	Input #3	Contact closure	Female
7	Input #4	Contact closure
8	–	No connection
9	–	Reserved

SIS™ Programmer’s Guide

Host to-scaler and scaler to host 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 DVS 304 determines that a command is valid, it executes the command and sends a response to the host device. All responses from the scaler 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.

Scaler-initiated messages

When a local event such as a front panel selection or adjustment takes place, the DVS 304 scaler responds by sending a message to the host. No response is required from the host. The scaler-initiated messages are listed here.

The DVS 304 sends the copyright message when it first powers on. Vx.xx is the firmware version number.

In X! All ]

Reconfig ] (where X! is the input number). The DVS 304 sends this response when an input is switched.

Using the command/response tables

The following are either Telnet (port 23) or Web browser (port 80) commands. There are some minor differences when you are implementing these commands via Telnet or via URL encoding using a Web browser. All commands listed below will work using either connection method but, due to some limitations of the Web browser, the encapsulation characters are modified to make sure that the Web browser will properly handle them. All examples in the command/response table show the proper implementation in a Telnet or Web browser session.

NNote for Web browsers: all non-alphanumeric characters must be represented as their hex equivalent, such as %xx where xx equals the two character representation of the hex byte that needs to be sent (e.g., a comma would be represented as %2C).

Extron electronic DVS 304 AD, DVS 304 D manual Serial Communication, SIS Programmer’s Guide