CDM-Qx Satellite Modem

Revision 4

Remote Control

MN/CDMQx.IOM

C.4

Packet Structure

 

 

 

 

 

 

 

Controller-to-target:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Start of

Target

Address

Instruction

 

Code Qualifier

Optional

End of Packet

 

Packet

Address

De-limiter

Code

 

 

Arguments

 

 

<

 

/

 

 

= or ?

 

Carriage Return

 

ASCII code 60

(4 characters)

ASCII code 47

(3 characters)

 

ASCII code 61 or

(n characters)

ASCII code 13

 

 

 

 

 

 

63

 

 

 

(1 character)

 

(1 character)

 

 

(1 character)

 

(1 character)

 

 

Example:

<0135/TRQ=70.2345{CR}

 

 

 

 

 

Target-to-controller:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Start of

Target

Address

Instruction

 

Code Qualifier

Optional

End of Packet

 

Packet

Address

De-limiter

Code

 

 

Arguments

 

 

>

 

/

 

 

=,?,!,*,# or -

 

Carriage Return,

 

ASCII

(4 characters)

ASCII

(3 characters)

 

ASCII code 61,

(From 0 to n

Line Feed

 

code 62

 

code 47

 

 

63,33,42,35,

characters)

ASCII code 13,10

 

(1 character)

 

(1 character)

 

 

126

 

(2 characters)

 

 

 

 

 

 

(1 character)

 

 

 

 

Example:

>0654/RSW=32{CR} {LF}

 

 

 

 

Each of the components of the packet is now explained.

C.4.1 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.

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.

C-3

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Image 193
Mocomtech CDM-QX Packet Structure, Start Of Packet, Controller-to-target, Example 0135/TRQ=70.2345CR Target-to-controller