Packet Structure; Start Of Packet; Address - Comtech EF Data CDM-600L Installation And Operation Manual

CDM-600L Satellite Modem
Remote Control
16.5

Packet Structure

Controller-to-target:

Start of Packet

Target Address
<
ASCII code 60
(1 character) (4 characters)
Example:
Target-to-controller:
Start of Packet Target

Address

>
ASCII
code 62
(1 character) (4 characters)
Example:
Each of the components of the packet is now explained.
16.5.1 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.
16.5.2 Address
Up to 9999 devices can be uniquely addressed. In RS-232 applications this value is set to
0. In RS-485 applications, the permissible range of values is 1 to 9999. It is programmed
into a target unit using the front panel keypad.
IMPORTANT
Address
De-limiter
/
ASCII code 47
(1 character)
<0135/TFT=1 [CR]
Address Instruction
De-limiter
/
ASCII
code 47
(1 character) (3 characters)
>0654/RSW=32 [CR][LF]
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.
16–3
Instruction Code
Code Qualifier
= or ?
ASCII code 61
or 63
(3 characters) (1 character)
Code Qualifier
Code
=, ?, !, or *
ASCII code 61,
63, 33 or 42
(1 character)
Revision 2
MN/CDM600L.IOM
Optional End of Packet
Arguments
Carriage Return
ASCII code 13
(n characters) (1 character)
Optional End of Packet
Arguments
Carriage Return,
Line Feed
(From 0 to n ASCII code 13,10
characters) (2 characters)