Point Six Link Manager 4010-43, Manual

Page: 40 / 131

38

Communicating with the Link Manager Link Manager Manual
Communicating with the Link
Manager
Link Manager Protocol
The system for communicating with the Link Manager is based on a command-
response architecture. Every submitted command will receive a response, as long as
there is a connection. Successful commands are responded to with an echo of the
primary command, and if the command returns data, the data is appended to the
primary command echo after a comma (if the comma is part of the command). The
primary command is the submitted command string in its entirely or up to but not
including the first comma. Sending the next command before receiving a response
to the last command is an error.
Each command must be prefixed with an ASCII 02 character (STX) (on most
terminal emulation programs, type Ctrl-B) and must end with an ASCII 13 character
(CR) (on most terminal emulation programs, type Ctrl-M or Enter). This protocol
will work with all the Link Manager communication media: Serial port, Command
Radio (option) and TCP/IP.
Example
Command: <STX>S<CR>
Response: <STX>S,6,082701111800,na,na<CR>
Remarks: <STX> is an ASCII 02 (or Ctrl-B on the keyboard)
<CR> is an ASCII 13 (or Ctrl-M or Enter on the
keyboard)
There is an additional layer of communications protocol that is media-specific. This
has been added to ensure reliability when using media lacking built-in error
detection. This protocol is recommended to be used with the Link Manager’s
Command Radio, and Serial ports. The command must be prefixed with an ASCII 01
character (SOT) (on most terminal emulation programs, key in Ctrl-A), then
following the command with a 4-character ASCII hex CRC16. The command is
then terminated with an ASCII 13 character (CR) (on most terminal emulation
programs, key in Ctrl-M or Enter). The CRC16 must be calculated using the full
command but does not include the ASCII 01 (SOT) or the ASCII 13 (CR). An