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SERVSWITCH
™
BRAND MATRIX VIDEO SWITCH
4.3 Switching With (or Through) a Serial Device
To control the Matrix Video Switch through an attached PC or other serial device,
the serial device has to be able to communicate with the Switch. (You’ll need to set
the device to 1200 bps, 8 data bits, and no parity; the number of stop bits is irrelevant.)
Beyond that, the serial device needs to be able to mimic the Switch’s keypad
commands. (See Section 4.2 for a description of the command syntax.) When you
press a button on the keypad, a “make” code is sent to the Switch; when you release
a button, a “break” code is sent to the Switch. (If a button is held down, “make”
codes are sent repeatedly, but the Switch ignores all of them except the first one.)
Here are the values you need to send to the Switch to get it to change channels,
listed as both ASCII characters and hexadecimal values:
Keypad Make Code, Break Code,
Button ASCII (hex) ASCII (hex)
[1] ` (60) @ (40)
[2] a (61) A (41)
[3] b (62) B (42)
[4] c (63) C (43)
[0] o (6f) O (4f)
[*] k (6b) K (4b)
[.] n (6e) N (4e)
[Enter] t (74) T (54)
The same rules that govern keypad switching apply here: Until the switching
command is complete, each code must be followed by another within five seconds,
or the command will be aborted and the Switch will reset itself. Any invalid or
unexpected code will also cause the command to be aborted and the Switch to
reset itself.
There is a special set of codes that can be sent by (or through) the serial device
that will cause the Switch to respond with status values; these can be very useful in
automated systems:
• Send the Switch an ASCII “0” (zero, 30 hex) to have it return the revision level
of its firmware: an ASCII “1” (31 hex), for instance, for firmware version 1.
• Send the Switch an ASCII “1”, “2”, “3”, or “4” (31 hex through 34 hex
respectively) to have it return the status of the corresponding output channel:
It will reply with ASCII “1”, “2”, “3”, or “4” (31 hex through 34 hex) to indicate
that that output is switched to input #1, 2, 3, or 4 respectively, or it will reply
with ASCII “0” (zero, 30 hex) to indicate that that output is blanked.