Packet Structure; Start Of Packet; Address - Comtech EF Data CDM-700 Installation And Operation Manual

CDM-700 High Speed Satellite Modem
Remote Control

11.5 Packet Structure

Controller-to-target:

Start of Packet

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

Address

>
ASCII
code 62
(1 character) (4 characters)
Example:
Each of the components of the packet is now explained in the following sections.
11.5.1 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.
11.5.2 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.
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
IMPORTANT
own address.
Address Instruction
De-limiter Code
/
ASCII code 47
(1 character) (3 characters)
<0135/TFQ=0070.2345{CR}
Address Instruction
De-limiter Code
/
ASCII
code 47
(1 character) (3 characters)
>0654/RSW=32{CR}{LF}
11–3
Code Optional
Qualifier Arguments
= or ?
ASCII code 61
or 63
(1 character) (n characters)
Optional
Code Qualifier
Arguments
=, ?, !, or *
ASCII code 61,
63, 33 or 42 (From 0 to n
(1 character) characters)
Revision 5
MN/CDM700.IOM
End of Packet
Carriage Return
ASCII code 13
(1 character)
End of Packet
Carriage Return,
Line Feed
ASCII code 13,10
(2 characters)