Siemens SIMATIC S5 Manual page 103

Data Exchange with the Central Controller
The pulse duration modulation of the controller output signal (manipulated
variable) allows the use of switching control elements (contactor, triac etc.).
With manipulated variables close to 0%, very short ON times occur which reduce
the working life of mechanical actuators.
The same applies to manipulated variables close to 100%. In this case short OFF
times occur.
Example:
Such repeated and unnecessary switching can be prevented by using a response
value.
The module then reacts as follows:
The "residual value processing" means that a good control action is
achieved despite suppression of very short switching times.
4–36
sampling time 16 s
manipulated variable 3 %
IP244
C79000–B8576–C860–02