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7.4 OPERATIONAL CONFIGURATION
IMPORTANT: Before the AC 2000+ alarm/communications interface card can be used to
interface an external upstream programming device with RAYCHEM T2000 HTC control
modules, the AC 2000+ communication ports must be configured as described in Section 7.2.
The following sections give details of the configuration parameters for the AC 2000+ alarm/
communications interface card. These parameters can only be accessed using one of the AC
2000+’s communication ports, in conjunction with an external upstream programming device
that communicates using the Modbus serial or Modbus/TCP protocols. See Section 1.5.3 for
additional details regarding the Modbus mapping specific to the AC 2000+.
7.4.1 AC 2000+ TAG
When adding or editing the AC 2000+ Tag, only the following characters may be used: / - .
( ) # any upper case letter in the alphabet, and any number from 0 to 9. The Tag is always
terminated with a space character.
IMPORTANT: Tags must be at least one character in length and are limited to a maximum of
19 characters. When an external upstream programming device is communicating to several
AC 2000+ devices sharing the same communication wires, ensure that each AC 2000+ has a
unique Tag.
7.4.2 LOAD SHEDDING CONTROL
This parameter can be ENABLED or DISABLED and determines whether or not the AC 2000+
will issue load shedding commands to the control modules.
Load shedding commands, issued by the AC 2000+, are initiated by sending remote contact
input information, using a Modbus command, from an external upstream programming device
to the AC 2000+. In selected control modules, a load shedding command will override their
temperature control and force their outputs off until reset by the AC 2000+. See Sections
3.4.18 to 3-4-20, 5-3, 7-4-3, 7-4-6-7, and 7-4-7 as well as Appendix E in this manual for details
regarding the load shedding features and the related parameters.
7.4.3 LOAD SHEDDING ZONES
If the LOAD SHEDDING CONTROL parameter of the AC 2000+ is enabled, then a load shedding
command issued by the AC 2000+ can force control modules into load shedding mode. Four
different load shedding zones may be defined, to allow groups of control modules to be forced
into load shedding mode simultaneously.
If a zone is not set to be used for load shedding, then no control module in that zone will ever
be forced into load shedding mode.
If a zone is set to be used for load shedding, then before any control module in that zone can
be forced into load shedding mode, the AC 2000+ must receive a remote contact input status
(which activates load shedding for that zone) from an external device.
7.4.4 ALARM RELAY RETURN TIME
This parameter affects both the alarm and the warning relay driver outputs of the AC 2000+.
The ALARM RELAYS’ RETURN TIME defines the period of time for which the relay driver output
will revert back to its normal state each time a new alarm is detected.
When set to 0.0 seconds, the alarm/warning relay driver output will remain in its alarm/warning
state until all active alarms/warnings have been reset.
When set for any value greater than 0.0 seconds, the alarm/warning relay driver output will
switch (and remain) in the alarm/warning state when the first alarm/warning is detected. When
any subsequent alarm or warning is detected, the alarm/warning relay driver output will revert
back to its normal state for the programmed ALARM RELAYS’ RETURN TIME. Once this time
has expired, the alarm/warning relay driver output will return to its alarm/warning state until
another alarm/warning is detected, repeating the sequence.
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