Instruction Code Qualifier - Comtech EF Data CDM-625A Installation And Operation Manual

CDM-625A Advanced Satellite Modem
Serial-based Remote Product Management
8.4.1.5

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)
!
(ASCII code 33)
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=0950.0000 would mean "set the transmit frequency to 950 MHz."
The ' ?' c ode i s us ed as t he Query O perator ( QO) and i s us ed to i ndicate t hat t he Target should r eturn t he c urrent value of t he
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:
a. 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.
b. 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 t he C ontroller s ends an instruction t o s et a par ameter t o a p articular v alue, t hen, i f the v alue s ent i s not valid, t he T arget w ill
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.
If the Controller sends an instruction code which the Target does not recognize, the Target will acknowledge the message by echoing
the invalid instruction, followed by the ! character.
Example: XYZ!
Definition
Definition
8–5
Revision 0
MN-CDM625A