Comtech EF Data CRS-200 REDUNDANCY SWITCH - Manual (Page 49)

CRS-200 COMTECH COMMUNICATIONS CORPORATION
CRS-200 REDUNDANCY SWITCH - OPERATIONS MANUAL PAGE 47
2) From Target to Controller, the only permitted values are:
= (ASCII code 61)
? (ASCII code 63)
! (ASCII code 33)
* (ASCII code 42)
They have these meanings:
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=xxx.xxxx,
where xxx.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).
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 that the target does not recognize, the
target will acknowledge the message by echoing the invalid instruction, followed
by the ! character with. Example: XYZ!
MESSAGE ARGUMENTS
Arguments are not required for all messages. Arguments are ASCII codes for the characters
0 to 9 (ASCII 48 to 57), A to Z (ASCII 65 to 90), period (ASCII 46) and comma (ASCII 44).
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.