Extron • Matrix 100 • User’s Manual
Appendix A • RS-232 Matrix Programmer’s 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 100. After receiving a command,
the Matrix 100 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 lists)
3. Data (if any) – the number of bytes required for the data
4. 80h, 80h, followed by an “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 mis-match92h - security code error
The following error codes are related to specific commands.
Erc - see command Erc - see command Erc - see command
C0 - CMD7 C1 - CMD8 C2 - CMD11
C3 - CMD10 D3 - CMD1
A-3
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