Standby; Capacity Assist; Unit Rotation; Out Of Service - Black Box CRCW-12 User Manual

Cold row chilled water (cw)
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Chapter 4: E2 Controller
One controller may be designated as the workgroup lead and networked with the controllers from a series of up to 7 additional
A/C units. If configured for multi-unit operation, the workgroup lead controller display panel allows access to the same data and
group control sensor choices that are available from networked system controller display panels.

4.6.1.1 Standby

If the lead controller in the workgroup loses a signal acknowledgement from an active A/C unit in the group, that A/C unit is
deemed as failed or taken out of service. The failed unit will be replaced with the first available standby unit from the workgroup.
The standby unit is cycled on and designated as the new active unit.

4.6.1.2 Capacity Assist

The Capacity Assist option can be used to maximize efficiency for conservation of energy and to more precisely control capacity
at low demand. This feature enables Active A/C units to handle the demand up to a certain temperature/humidity setpoint and
then enables additional units to begin operating as needed. If the Active A/C units are running and unable to satisfy the demand,
Capacity Assist A/C unit(s) may be programmed to turn on to assist the Active units.
Each Capacity Assist unit may be set to control operation based on its local temperature/humidity sensor values or control opera-
tion based on network sensor values transmitted from the lead controller. Multiple Capacity Assist units are typically set with each
unit in the group assigned incrementally increasing/decreasing offsets for cooling, humidifying, and dehumidifying so they will
turn on one at a time only if the unit(s) currently operating are unable to satisfy the demand. They should incrementally turn off
as each unit reaches its cut-out setpoint, while active A/C unit(s) continue to maintain room conditions at the desired level.

4.6.1.3 Unit Rotation

In this mode, the lead controller will rotate duty between the grouped A/C units to promote equal run time and will rotate the
role of group lead. When set up for unit rotation, the A/C units will rotate duty in order of their group addresses. Active, Capacity
Assist, and Standby units are all in the rotation cycle, so even a standby unit will be cycled into active duty on a scheduled basis.
A/C units in the group may have their duty assignments locked so they do not join the rotation cycle (and cannot take the lead).
In this case, the message "No_Rot" appears after the duty assignment displayed in the main screen.
Figure 4-73. Unit rotation screen.
An Active_No_Rot unit is always On, therefore, it will not rotate out. An Active_No_Rot unit will still be able to take the role as
lead controller during a rotation. Units designated as "Out of Service" do not rotate nor can they be used as lead units.
The rotation time period is typically 1 week, however it may be set by the user via the Factory menu. Contact Black Box Technical
Support at 724-746-5500 or info@blackbox.com for assistance when accessing the Factory menu.

4.6.1.4 Out of Service

A unit may be removed from the group entirely by placing it Out of Service. In this mode, the unit will not operate. A unit may be
placed in this mode as a safety measure to prevent it from unexpectedly starting when performing maintenance or repairs.

4.6.2 Configuring a Workgroup

A workgroup can consist of up to 8 controllers (I/O boards) with pLAN addresses 1 to 8. Their corresponding display terminals will
be assigned pLAN addresses from 32 down to 25. The E2 controller program is defaulted with the controller address set to 1 and
its terminal (display) address set to 32. As such, a normal standalone controller does not need any changes made to either the
controller or the terminal address. The method to setting up workgroups is to retain the first (group lead) controller's pLAN
address as #1 and terminal address as #32 so that the sum of the addresses equals 33. The first controller added to the group is
assigned pLAN address #2 and its terminal is assigned address #31, the sum of which again equals 33.
NOTE: The sum of the controller and terminal address numbers must always equal 33.
724-746-5500 | blackbox.com
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