VC1000 Focus Guide - ProLon

VAV Controller
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• Math 1-5: The output is calculated using the chosen math function. In a
standard ProLon Modbus network, the VAV Controller will use the math
functions provided by the network master. In Lon or BACnet, setting an output
to use math functions will automatically activate the VAV Controller’s own math
calculations (even if this was not enabled in the Math Functions configuration
screen). See the Math Functions configuration screen on p.33 for more details.
• Off: The output remains inactive and will not appear on the Home screen.
2.1.5.1 Setpoint Selection*
• Heating Setpoint: The desired setpoint in heating mode. Setpoint cannot be zero.
• Cooling Setpoint: The desired setpoint in cooling mode. Setpoint cannot be zero.
2.1.5.2 Control Mode Selection*
• Proportional Band: In proportional band control, the output is zero when the demand
reaches the setpoint, increases proportionally with the demand by pulsing (Outputs 1
to 4) or modulating (Output 5), and finally reaches 100% when the demand reaches
the setpoint + proportional band (see figure below). The sum of the setpoint and the
demand cannot be greater than 100%.
Proportional Band
0%
Output = 0% Output = 100%
Demand
Setpoint
Figure 2.1.12: Proportion deadband diagram
Ex.: Setpoint = 25%
Proportional band = 50%
Demand = 45%
Output = ((45-25)x100)/50 = 40%
• Differential: In differential mode, the output alternates between 0 and 100% (ON/OFF).
From an OFF state, the output becomes ON when the demand passes (setpoint +
differential/2) and remains ON until the demand goes back down below (setpoint –
differential/2) (see figure below). The setpoint must always be greater then the
differential. The sum of the setpoint and the differential must be less than 100%.
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