Address Delimiter; Instruction Code; Instruction Code Qualifier - Comtech EF Data CDM-710 Installation And Operation Manual

CDM-710 Broadcast Satellite Modem
Appendix A
A.5.3

Address Delimiter

This is the "forward slash" character '/' (ASCII code 47).
A.5.4

Instruction Code

This is a three-character alphabetic sequence, which identifies the subject of the message. Wherever possible, the instruction codes have been
chosen to have some significance – e.g., TFQ for transmit frequency, RMD for receive modulation type, etc. This aids in the readability of
the message, should it be displayed in its raw ASCII form. Only upper case alphabetic characters may be used (A-Z, ASCII codes 65 - 90).
A.5.5

Instruction Code Qualifier

This is a single character, which further qualifies the preceding instruction code. Code Qualifiers obey the following rules:
1. From Controller-to-Target, the only permitted values are:
Symbol
=
(ASCII code 61)
?
(ASCII code 63)
2. From Target-to-Controller, the only permitted values are:
Symbol
=
(ASCII code 61)
?
(ASCII code 63)
The '=' code is used as the Assignment Operator (AO) and is used to indicate that the parameter defined by the preceding
byte should be set to the value of the argument (s) which follow it.
Example: in a message from Controller-to-Target, TFQ=0070.0000 would mean "set the transmit frequency to 70 MHz."
The '?' code is used as the Query Operator (QO) and is used to indicate that the Target should return the current value of
the parameters defined by the preceding byte.
Example: in a message from Controller-to-Target, TFQ? Would mean "return the current value of the transmit frequency."
The '=' code is used in two ways:
First, if the Controller has sent a query code to a Target
Example: TFQ? (meaning 'what's the Transmit frequency?'), the Target would respond with TFQ=xxxx.xxxx, where
xxxx.xxxx represents the frequency in question.
Second,If the Controller sends an instruction to set a parameter to a particular value, then, providing the value sent is
valid, the Target will acknowledge the message by replying with TFQ=(with no message arguments)
If the Controller sends an instruction to set a parameter to a particular value, then, if the value sent is not valid, the Target
will acknowledge the message by replying (for example) with TFQ? (with no message arguments). This indicates that there
was an error in the message sent by the Controller.
Definition
Definition
A–4
Revision 11
MN/CDM710.IOM