Comtech EF Data CDM-625A - Manual (Page 317)

CDM-625A Advanced Satellite Modem MN-CDM625A
Serial-based Remote Product Management Revision 3
8–5
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 Definition
=
(ASCII code 61)
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.”
?
(ASCII code 63)
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.”
2) From Target-to-Controller, the only permitted values are:
Symbol Definition
=
(ASCII code 61)
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).
?
(ASCII code 63)
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.
!
(ASCII code 33)
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!
*
(ASCII code 42)
If the Controller sends an instruction to set a parameter to a particular value, then, if the value sent is valid BUT the modulator will not
permit that particular parameter to be changed at this time, the Target will acknowledge the message by replying, for example, with
TFQ* (with message arguments).