ABB i-bus KNX ABA/S 1.2.1 - Page 93

ABB i-bus
®
KNX
Parameters
ABA/S 1.2.1 | 2CDC509086D0201 93
Function
Schematic diagram of controller:
Fig. 20: Schematic diagram of controller
Algorithms:
• ControlValue = ProportionalValue + IntegralValue + DerivativeValue
• ProportionalValue = Deviation x ProportionalCoefficient
• IntegralValue = IntegralValueOld + Deviation x CycleTime / IntegralTime
• DervativeValue = (Deviation - DeviationOld) / CycleTime x DerivativeTime
The controller calculates a new output value during the calculation cycle time of the logic engine (see
Cycle time) (usually every 200 ms). The output sends on value change.
If the ControlValue exceeds the Upper limit or Lower limit (see parameters), the values are limited
accordingly and the IntegralValue is reduced.
If the Reset input = 1: the IntegralValue is set to 0.
Exception handling
For unlinked parameter inputs (Proportional Coefficient, Integral Time, Derivative Time) the function
element uses a 0.
Bus voltage failure, download and restart
The integral value is saved. The value is restored on restart.