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CDM-840 Remote Router Revision 0
Appendix B MN-CDM840
B–4
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: CMD? meaning “what’s the value of this parameter?”), the
Target would respond with CMD=xxx, where xxx represents the parameter 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 CMD=(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 CMD? (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: CMD!
*
(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 CMD* (with message arguments).
#
(ASCII code 35)
If the Controller sends a correctly formatted command, BUT the unit is not in remote mode, it will not allow reconfiguration
and will respond with CMD#.
B.4.6 Optional Message Arguments
Arguments are not required for all messages. Arguments are ASCII codes for the characters 0 to 9 (ASCII codes 48 to 57), period (ASCII
code 46) and comma (ASCII code 44).
B.4.7 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 codes 13 and 10). Both indicate the
valid termination of a packet.