Siemens SIMOVERT MASTERDRIVES Manual page 174

Functions
7.1.2.2 Influencing the time response
Calculation
workload
Control response
7-8
The time response affects two different areas:
♦ Calculation workload
♦ Control response
You can influence the calculation workload as follows:
♦ By changing the sampling frequency P340. With a high sampling
frequency, less calculating time is available per time slot. With a low
sampling frequency, more calculating time is available per time slot.
♦ By assigning function blocks to different time slots.
If you assign too many function blocks to one time slot, it is no longer
possible to process all function blocks within the specified time. The
time monitoring facility generates an alarm and de-energizes the unit if
the alarm occurs repeatedly.
You can influence the control response as follows:
♦ By changing the sampling frequency P340. With a high sampling
frequency, the reaction time is shorter. With a low sampling
frequency, the reaction time is longer.
♦ Change parameter P357. Setting parameter P357 to 1 will also
impair the reaction time as current control only takes place in time
slot T1 which corresponds to the sampling frequency P340 being
halved.
♦ By assigning function blocks to other time slots.
♦ By changing the processing sequence.
♦ By changing time-relevant parameters.
If you assign a function block to a slow time slot (e.g.T10), the result of
this function block is seldom re-calculated, i.e. the long processing time
acts on the control circuit as a delay element. If you change the
processing sequence of two consecutive function blocks by having one
output block calculated before its associated input block, you will have
integrated a delay element of the duration of one time slot into the
control circuit.
6SE7087-6QX70 (Version AG)
Compendium Motion Control
05.2006
Siemens AG
SIMOVERT MASTERDRIVES