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Serial Interface Operation
CDM-760 Advanced High-Speed Trunking Modem
1. If the Controller sends a query to the Target. For example: <0/TFQ? (meaning "what is the current value of the transmit frequency?") – the
Target responds with >0000/TFQ=xxxx.xxxx, the value for that queried parameter.
2. If the Controller sends an instruction to set a parameter to a particular value, and the value sent is valid, the Target acknowledges the
message and responds with >0000/TFQ=(with no message arguments).
? (ASCII Code 63)
If the Controller issues a command to set a parameter to a particular value, and the value sent is not valid, the Target then acknowledges the
message and responds with '?'. This indicates that there was an error in the message sent by the Controller.
For example: >0000/TFQ? (with no message arguments).
! (ASCII Code 33)
If the Controller issues a command that the Target does not recognize, the Target responds by echoing the invalid instruction code, followed by
'!'.
For example: >0000/ABC!
* (ASCII Code 42)
If the Controller issues a command to set a parameter to a particular value, and the value sent is valid BUT the modem will not permit that
particular parameter to be changed at present, the Target responds by echoing the valid instruction code, followed by '*'.
For example: >0000/TFQ* (with message arguments)
# (ASCII Code 35)
If the Controller sends a correctly formatted command, BUT the Target is not in Remote Mode, the unit does not allow reconfiguration and
responds by echoing the valid instruction code, followed by '#'.
For example: >0000/TFQ#
∼ (ASCII Code 126)
If a message is sent via a local modem to a distant end device or ODU, the message is transmitted transparently through the local modem. In the
event of the distant-end device not responding, the local modem responds by echoing the instruction code, followed by '~'.
For example: A response of >0001/RET~ indicates that the modem is no longer waiting for a response from the distant end device, and it is now
ready for further communications.
8–6
Revision 3
MN-CDM760
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