Mocomtech CDM-570 - Manual (Page 13)

CDM570/570L Satellite Modem MN/CDM570L.AA4
Incorporate NMCS Protocol
Page 9 of 54 MN/CDM570L.AA4
3.3.4.2 Target to Controller
The only permitted values are:
= (ASCII code 61)
! (ASCII code 33)
= Code The = code (target to controller) is used in two ways:
First, if the controller has sent a query code to a target (for 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 in the argument is valid, the target will
acknowledge the message by replying with TFQ= (with no message
arguments).
! Code 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.
If the controller sends an instruction to set a parameter to a particular value, and, if the
value sent in the argument is valid, BUT the modem will not permit that particular
parameter to be changed at that time, then the target will acknowledge the message by
replying (for example) with TFQ! (with no message arguments).
If the controller sends an instruction code which the target does not recognize, then the
target will acknowledge the message by echoing the invalid instruction, followed by the !
character. Example: XYZ!
Right now the CDM software is not organized to categorize various error codes, so it
combines various errors into a single code (!).