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CDM-625 Advanced Satellite Modem
Appendix D
D.4.1
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.
Start of Packet
<
ASCII code 60
(1 character)
Example: <0135/TFQ=70.2345{CR}
Start of Packet
>
ASCII code 62
(1 character)
Example: >0654/RSW=32{CR}{LF}
D.4.1.1 Start of Packet
•
Controller-to-Target: This is the character '<' (ASCII code 60).
•
Target-to-Controller: This is the character '>' (ASCII code 62).
The '<' and '>' characters indicate the start of packet. They may not appear anywhere else within the body of the message.
Target Address
Address Delimiter
/
ASCII code 47
(4 characters)
(1 character)
Target Address
Address Delimiter
/
ASCII code 47
(4 characters)
(1 character)
Controller-to-Target
Instruction Code
Code Qualifier
= or ?
ASCII codes 61 or 63
(3 characters)
(1 character)
Target-to-Controller
Instruction Code
Code Qualifier
=, ?, !, or *
ASCII codes
61, 63, 33, or 42
(3 characters)
(1 character)
D–3
Revision 13
MN-CDM625
Optional Arguments
End of Packet
Carriage Return
ASCII code 13
(n characters)
(1 character)
Optional Arguments
End of Packet
Carriage Return, Line
Feed
ASCII codes 13,10
(From 0 to n characters)
(2 characters)
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