Comtech EF Data CDM-500 - Manual (Page 70)

CDM-500 Closed Network Satellite Modem Remote Control
Rev. 1.3 B–5
Second, if the controller sends an instruction to set a parameter to a particular
value, then, providing the value sent in the argument is valid, the target will
acknowledge the message by replying with TFQ= (with no message arguments).
The ? code (target to controller) is only used as follows:
If the controller sends an instruction to set a parameter to a particular value, then,
if the value sent in the argument 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.
The * code (target to controller) is only used as follows:
If the controller sends an instruction to set a parameter to a particular value, then,
if the value sent in the argument is valid, BUT the modem will not permit that
particular parameter to be changed at that time, the target will acknowledge the
message by replying (for example) with TFQ* (with no message arguments).
The ! code (target to controller) is only used as follows:
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 with.
Example: XYZ!
B.5.5 Message Arguments
Arguments are not required for all messages. Arguments are ASCII codes for the
characters 0 to 9 (ASCII 48 to 57), period (ASCII 46) and comma (ASCII 44).
B.5.6 End Of Packet
Controller to Target: This is the ‘Carriage Return’ character (ASCII code 13)
Target to Controller: This is the two-character sequence ‘Carriage Return’, ‘Line Feed’.
(ASCII code 13, and code 10.)
Both indicate the valid termination of a packet.