Comtech EF Data LPODnet - Manual (Page 36)

LPODnet M&C Netbook Accessory Revision 3
Ethernet-Based M&C using the LPODnet MN-LPODNET
3–6
Because this is used to provide a reliable indication of the start of packet, these two characters
may not appear anywhere else within the body of the message.
3.5.1.1.2 Target Address
Up to 9,999 devices can be uniquely addressed. In EIA-232 applications this value is set to 0. In
EIA-485 applications, the permissible range of values is 1 to 9999.
The Controller sends a packet with the address of a Target – the destination of the
packet. When the Target responds, the address used is the same address, to indicate
to the Controller the source of the packet. The Controller does not have its own
address.
3.5.1.1.3 Address Delimiter
This is the forward slash character ' / ' (ASCII code 47).
3.5.1.1.4 Instruction Code
This is a three-character alphabetic sequence that identifies the subject of the message.
Wherever possible, the instruction codes have been named to have some significance.
For example: GAC for Global Amplifier Configuration; IPA for IP Address, etc. This aids in the
readability of the message, should it be displayed in its raw ASCII form. Both upper case and
lower case alphabetic characters may be used (A-Z and a-z, ASCII codes 65-90 and 97-122).
3.5.1.1.5 Instruction Code Qualifier
This single character further qualifies the preceding instruction code. Code Qualifiers obey the
following rules:
1. From Controller-to-Target, the only permitted characters are:
=
(ASCII code 61 This character is used as the assignment operator, and is used to indicate that the
parameter defined by the preceding byte should be set to the value of the argument(s)
that follow it. For example: In a message from Controller-to-Target, MUT=1 would mean
‘enable the Mute function’.
?
(ASCII code 63) This character is used as the query operator, and is used to indicate that the Target
should return the current value of the parameter defined by the preceding byte. For
example: In a message from Controller-to-Target, SWR? would mean ‘returns the value
of the internal software revision installed in the unit’.