Extron Electronics Matrix 200 - Manual (Page 94)

Extron • Matrix 200 • User’s Manual
Appendix B • Programming Guide
Host-Initiated Communications Protocol
Most of the information transfer activity is initiated by a Host system through a
control port. For example, the Host can send Commands to the Matrix to request
data from or send data to the Matrix 200. After receiving a command, the Matrix
200 executes it and sends back a Response to the Host. The Response includes
an error code together with any requested data.
The Response includes the original Command code. Its format is as follows:
1. Command code CMD byte (plus SCMD for some commands)
2. Error code Erc (see list)
3. Data (if any)
4. Checksum
Cks
5. End of transmission mark EOT
Error Codes (Erc)
The error code is usually bit-encoded and follows the data format (bit-7 always
“1” to indicate a data byte). An error code of 80 (hex) indicates “no error”. Other
error codes specify the reason for not properly executing a command. The first
error condition encountered will determine the error code. The following list has
Erc codes that could occur in response to any command, and others that are
associated with specific commands. (See command for description.)
Erc description Erc description Erc description
80h no error (normal) 81h checksum error 82h illegal command
90h no I/O boards 91h system mismatch 92h security code error
Erc see command Erc see command Erc see command
C0 CMD7 C1 CMD8 C2 CMD11
C3 CMD10 C4 CMD23 C5 CMD14
C6 CMD14 C7 CMD16 C8 CMD16
C9 CMD1 CA CMD16 CB CMD16
CC CMD16 CD CMD18 CE CMD18
CF CMD18 D0 CMD18 D1 CMD20
D2 CMD35 D3 CMD1 D4 CMD36/37
Matrix-Initiated Communications Protocol
Sometimes, under abnormal conditions, the Matrix 200 may detect a situation
that must be reported to the Host. For example: Auxiliary power supply is
activated, memory error, backup battery must be replaced, etc. These Matrix
Reports are listed and explained later. They have the same general command
format as the Host-initiated commands, but no response is expected from the
host.
Timing
When Commands are sent to the Matrix 200 switcher, the response is delayed
due to normal processing time. The response time has two components: RS-232/
RS-422 bus delay and Matrix 200 processing time. Matrix 200 processing time is
variable, depending on the length of the command and the matrix size.
Response time is usually less than 100 msec.
B-6