Packet Structure; Start Of Packet; Target Address - Comtech EF Data CDM-710 Installation And Operation Manual

CDM-710 Broadcast Satellite Modem
Appendix A
A.5

Packet Structure

Start of Packet

<
ASCII code 60
(1 character)
Example: <0135/TFQ=0070.2345{CR}
Start of Packet
>
ASCII code 62
(1 character)
Example: >0654/RSW=32{CR}{LF}
A.5.1 Start of Packet
Controller-to-Target: This is the character '<' (ASCII code 60).
Target-to-Controller: This is the character '>' (ASCII code 62).
Because this is used to provide a reliable indication of the start of packet, these two characters may not appear anywhere else within the
body of the message.
A.5.2

Target Address

Up to 9999 devices can be uniquely addressed. In EIA-232 applications this value is set to 0. In EIA-485 applications, the permissible
range of values is 1 to 9999. It is programmed into a Target unit using the front panel keypad.
The Controller sends a packet with the address of a Target – the destination of the packet. When the Target responds,
the address used is the same address, to indicate to the Controller the source of the packet. The Controller does not
have its own address.
IMPORTANT
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)
A–3
Revision 11
MN/CDM710.IOM
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)