Mocomtech CDM-570, CDM-570L 13.5 Packet Structure , 13.5.1 Start Of Packet , 13.5.2 Address

CDM-570/570L Satellite Modem with Optional IP Module Revision 4
Serial Remote Control MN/CDM570L.IOM
13–3
13.5 Packet Structure
Controller-to-target:
Start of
Packet
Target
Address
Address
De-limiter
Instruction
Code
Code Qualifier Optional
Arguments
End of Packet
<
ASCII
code 60
(1 character) (4 characters)
/
ASCII
code 47
(1 character) (3 characters)
= or ?
ASCII code 61
or 63
(1 character) (n characters)
Carriage Return
ASCII code 13
(1 character)
Example: <0135/TFQ=1949.2345{CR}
Target-to-controller:
Start of
Packet
Target
Address
Address
De-limiter
Instruction
Code
Code Qualifier Optional
Arguments
End of Packet
>
ASCII
code 62
(1 character) (4 characters)
/
ASCII
code 47
(1 character) (3 characters)
=, ?, !, *, # or ~
ASCII code 61, 63,
33, 42, 35, 126
(1 character)
(From 0 to n
characters)
Carriage Return,
Line Feed
ASCII code 13,10
(2 characters)
Example: >0654/RSW=32{CR}{LF}
Each of the components of the packet is now explained.
13.5.1 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.
13.5.2 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
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.