Comtech EF Data LPODnet - Manual (Page 37)

LPODnet M&C Netbook Accessory Revision 3
Ethernet-Based M&C using the LPODnet MN-LPODNET
3–7
2. From Target-to-Controller, the only permitted characters are:
(ASCII code 61) This character is used in two ways:
First, if the Controller has sent a query code to a Target (for example: MUT?, meaning
‘is the Mute enabled or disabled?’), the Target would respond with MUT=x, where x
represents the state in question: 1 being ‘enable’ and 0 being ‘disable’.
Second, if the Controller sends an instruction to set a parameter to a particular value,
and if the value sent in the argument is valid, then the Target will acknowledge the
message by replying with MUT= (with no message arguments).
?
(ASCII code 63) This character is only used 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 MUT? (with no message
arguments). This indicates that there was an error in the message sent by the Controller.
!
(ASCII code 33) This character is only used 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: XYZ!
*
(ASCII code 42) This character is only used 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 Target is in the
wrong mode (e.g., standby mode in redundancy configuration) and will not permit that
particular parameter to be changed at that time, the Target will acknowledge the
message by replying, for example, with MUT* (with no message arguments).
#
(ASCII code 35)
This character is only used if the Controller sends an instruction code which the Target
cannot currently perform because of hardware resource issues, then the Target will
acknowledge the message by echoing the invalid instruction, followed by the #
character. This response can only occur if the operator sends two or more ‘hardware
configuration’ type commands without allowing adequate time between commands for
the hardware to be configured. For example, if the operator issued commands to change
both the frequency and the attenuation with less than 100 milliseconds between
commands, and if this response is returned, then the command has not been accepted
and the operator must resend the command.
3.5.1.1.6 Optional Message Arguments
Arguments are not required for all messages. Arguments are ASCII codes for any printable
character.
3.5.1.1.7 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' (ASCII code 13)
and 'Line Feed' (ASCII code 10).
Both indicate the valid termination of a packet.