Power Line Carrier
GARD 8000 SYS RFL Electronics
April 23, 2015 10-7 973.334.3100
during deployment, and the operating parameters of the system are set accordingly and maintained in
non-volatile memory of the Module.
In order to determine that the link is operating normally, a checkback process is used to test the link.
For the purposes of checkback, the Module at the near end of the link is defined as the Master and the
Module at the far end of the link is defined as the Remote. During checkback, a pre-defined sequence
of on-off states (checkback codes) is transmitted by the Master to the Remote which responds with an
acknowledgement on a successful reception.
The Remote responds in one of two ways depending on how the Master terminates its transmission of
the Checkback Code. If the Master leaves the tone on for 5 seconds after the last bit of the Checkback
Code, the Remote responds in Hard Carrier Mode. Otherwise, the Remote responds in Normal Mode.
In Normal Mode, the Remote responds by transmitting a pre-defined sequence of on-off states (called
the Acknowledgement Code) to the Master. In Hard Carrier Mode, the Remote responds by
transmitting a tone to the Master for a pre-defined length of time.
Four, Hard carrier transmitted codes and two received codes can be programmed into either the master
or remote units. Operation from either end is possible.
Checkback may be initiated automatically by either the Master or the Remote. It may also be initiated
manually by the user. Remote initiation is accomplished by sending a specific code to the master. This
code tells the master to initiate a test sequence. This code is not available as a response code from
remotes for normal tests.
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