Comtec CDM-840 - Packet Structure

CDM-840 Remote Router MN-CDM840
Serial-based Remote Product Management Revision 3
7–4
For Serial Remote Control, all issued commands (Controller-to-Target) require a response (Target-to-Controller). This response is
either to return data that has been queried by the Controller, or to confirm the Target’s receipt of a command to change the Target’s
configuration.
7.2.2 Packet Structure
The exchange of information is transmitted, Controller-to-Target and Target-to-Controller, in packets. Each packet contains a finite
number of bytes consisting of printable ASCII characters, excluding ASCII code 127 (DELETE).
In this context, the Carriage Return and Line Feed characters are considered printable. With one exception, all messages from Controller-
to-Target require a response – this will be either to return data that has been requested by the Controller, or to acknowledge reception of an
instruction to change the configuration of the Target.
Controller-to-Target (Issued Command or Query)
Start of Packet Target Address Address Delimiter Instruction Code Code Qualifier Optional Arguments End of Packet
<
ASCII Code 60
(1 character)
0000 (default)
(4 characters)
/
ASCII Code 47
(1 character)
(3 characters)
=or ?
ASCII Codes 61 or 63
(1 character)
(n characters)
Carriage Return
ASCII Code 13
(1 character)
Packet “issued command” example: <0000/RSH=30[cr]
Packet “issued query” example: <0000/TFQ?[cr]
Target-to-Controller (Response to Command or Query)
Start of Packet Target Address Address Delimiter Instruction Code Code Qualifier Optional Arguments End of Packet
>
ASCII Code 62
(1 character)
0000 (default)
(4 characters)
/
ASCII Code 47
(1 character)
(3 characters)
=, ?, !, *, #
(ASCII Codes 61, 63,
33, 42, or 35)
(1 character)
(n characters)
Carriage Return
ASCII Code 13
(1 character)
Packet example – response received for issued query: >0000/BBU=107[cr][lf]
Detailed description of the packet components follow.