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.
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