Extron electronic MLA-VC10 user manual Installation and Setup, cont’d Operation, RS-232 control

Installation and Setup, cont’d

Operation

To control audio volume when using an MLA-VC10, turn a connected MediaLink Controller’s Volume knob, or send commands via an RS-232 remote control device such as a computer or third party control system.

If you are using an MLC with the MLA-VC10, use the

Controller (MLC) Config portion of the MediaLink control software (included with the MLC) to set the

MLC’s volume control to “Switcher” instead of “Projector” . Refer to the MediaLink Controllers User’s Manual for details.

RS-232 control

The RS-232 protocol for the MLA-VC10 is 9600 baud, 1 stop bit, no parity, and no flow control.

The control device (host) can use Extron’s Simple Instruction Set (SIS) commands.

The MLA’s MLC/Power 5-pole captive screw connector has the following pin assignments:

A = transmit, B = receive, C = not used, = ground, + = +12VDC input

Host-to-MLA 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 interface executes the command and sends a response to the host device. All respon- ses from the interface 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.

MLA-initiated messages

When the MLA is powered up, it sends the following message (underlined here) to the host:

(C) Copyright 2002, Extron Electronics, MLA-VC10

No response is required from the host. The MLA may also send a message of Volxxx where xxx represents the setting for the percentage of maximum volume.

Error response

When the MLA receives a valid SIS command, it executes the command and sends a response to the host device. If the MLA is unable to execute the command because the command contains invalid parameters, it returns the following error response to the host:

E13 – Invalid value (the number is out of range/too large)

Using the command/response table

The command/response table lists valid command ASCII codes, the MLA’s responses to the host, and a description of the command’s function or the results of executing the command. Lower case characters are acceptable in the command field unless otherwise indicated. The following ASCII to HEX conversion table is for use with the command/response table.

ASCII to HEX Conversion Table

•

Symbol definitions

= CR/LF (carriage return/line feed) (hex 0D 0A)

•= Space

X1	=	Volume adjustment range (0 through 100%)
X2	=	On/off status
		0	= off/disable
		1	= on/enable
X3	=	Controller firmware version (listed to
		two decimal places e.g.: x.xx)

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