Theben KNX Series User Manual

Appendix
RAMSES 718 P / RAMSES 718 S 86
6.2 PWM cycle
6.2.1 Basic principle
The 50% control variable is converted into switch-on/switch-off cycles in order to achieve a
heating output of 50%.
The actuator is switched on for 50% of the time and switched off for 50% of the time over a
fixed period (10 minutes in our example).
Example: 2 different turn-on times of 2 and 7 minutes indicate the implementation of 2
different actuating values, that is once 20% and once 70% during a PWM period of 10 minutes.
On
Off
1
2
3
4
5
6
7
8
9
10
1
2
3
4
5
6
7
8
9
10
min
PWM period 10 min
Actuating value 20%
PWM period 10 min
Actuating value 70%
6.2.2 Response to changes in the actuating value
 Every change in the actuating value is immediately transferred to the PWM cycle in order
to respond to changes in the quickest possible time.
The last actuating value was 20% (A).
A new actuating value of 50% is received during the cycle (B).
The output is immediately switched on and the missing 30% switch-on time is
added.
The next cycle is executed with 50% (C).
A
C
On
20% + 30% = 50%
Off
1
2
3
4
5
6
7
8
9
10
1
2
3
4
5
6
7
8
9
10
min
B
Example 1:

Theben KNX Series Specifications

General

Communication Protocol	KNX
Ambient Temperature	-5°C to +45°C
Storage Temperature	-25°C to +70°C
Protection Class	IP20
Relative Humidity	5% to 95%, non-condensing
Operating Voltage	24 V DC (via KNX bus)