ABB i-bus
®
KNX
Planning and application
FCC/S 1.X.X.1 | 2CDC 508 200 D0211 Rev A 367
Fig. 64: Pulse width modulation (PWM)
2CDC072010F0118
With pulse width modulation, a relatively accurate setting of the temperature can be achieved with-
out any resulting overshoots. Simple valve drives can be used. The positioning frequency of the
control value is relatively high.
Pulse width modulation can be used with the device in conjunction with Electromotor or Elec-
trothermal Valve Drives.
12.5.1.1.1
Example
When the device receives a 1-byte control value (continuous control) as an input signal, this value
together with the parameterized cycle time from a PWM calculation is converted into a signal for 2-
point control (ON-OFF-ON).
With PWM control, the received control value (0...100 %) calculated in the control algorithm is con-
verted to a pulse width modulation. The conversion is based on a constant cycle time. If the device
receives a control value of 20 % and the cycle time is 15 minutes, the valve will be opened for
3 minutes (20 % of 15 minutes) and closed for 12 minutes (80 % of 15 minutes).
