CE Labs, Inc.
SW404 / SW808 Switch Protocol
April 4, 2008
Rev. A
Addendum – Additional RS232/RS485 protocol information
CRC calculation:
The CRC is calculated as below. The CRC is optional for commands sent to the switch. If the
CRC is not used, bit 6 in first byte of command packet should be set to 0, otherwise 1 to utilize
the CRC. Note: A CRC byte is always appended to responses from the unit.
CRC-8-Dallas/Maxim
x
8
+
x
5
+
x
4
+ 1 (1-Wire bus) 0x31 or 0x8C (0x19)
Polynom
31H
Inverted
8CH
Initial
00H
Final Xor
00H
Input Data
Reversed (Reflected)
Final Result
Reversed (Reflected)
Command Examples:
Numbers are Hex Bytes. Requests are shown with CRC and without CRC.
The response is the same whether or not CRC is appended to request
*******************************************************************
Request machine info and model
Request: 20 3F 00 00 F1 (or 00 3f 00 00)
Response: 80 0A C4 04 04 59 58 2D 33 30 34 34 C8
Y X - 3 0 4 4
Audio and video supported, 4 output x 4 input,
4 memory locations, name = YX-3044
*******************************************************************
Request audio status for all, put in memory location 0
Request: 20 08 00 00 55 (or 00 08 00 00)
Response: 80 08 01 04 02 00 03 00 04 00 65
Output 1 to Input 4, Output 2 disconnected,
Output 3 disconnected, Output 4 disconnected