LeadLagCycles provides lead-lag control of from 2 to 10 BooleanWritables based upon their accumulated COS (change of state)
counts. This object balances the number of change of states cycles of each of the devices. Only one of the controlled devices
will be active at a time based on cycle count.
LeadLagCycles is available in the HVAC folder of the kitControl palette, along with a similar LeadLagRuntime object.
Setup of the object involves the following properties:
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In
A StatusBoolean input that controls whether any control device should be on. If this input is true, one of the outputs will be active based on the cycle count of each controlled device.
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Number Outputs
Specifies the number of devices (outputs) that are controlled.
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Max Runtime
Specifies the maximum amount a given output will be true before switching to another output.
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Feedback
A StatusBoolean input, to provide positive feedback that a controlled device actually started. If the feedback value does not show true within the Feedback Delay time, the current controlled output will show alarm, and the LeadLagCycles switches to the next controlled output. Setting this value to true (and not linking) disables this alarm feature.
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Feedback Delay Time
Specifies the delay time used to evaluate the feedback link (if any)
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Out A—J
StatusBoolean outputs, each typically linked to a BooleanWritable control point with a DiscreteTotalizerExt. Outputs are typically used to control loads of some type, such as 2 or more pumps.
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Cycle Count A—J
These are Integer inputs that are used for cycle count feedback for the corresponding Out A - J. These inputs will typically be linked to the ChangeOfStateCount property of the DiscreteTotalizerExt that is measuring the cycles of the corresponding Out A - J.
Example 10. Using the LeadLagCycle component
A simple example LeadLagCycle object that controls 3 pumps is shown in Figure 23 and Figure 24.
Note that in this example, each of the three BooleanWritable points has a DiscreteTotalizerExt, with its changeOfStateCount slot linked back to a Cycle Count x input on the LeadLagCycles object. The “feedback” Or object simulates feedback, fed through a BooleanDelay object.