Communication Management for SIMATIC S7
7.3
Optimization
Acquisition cycle and update time
The acquisition cycles defined in the configuration software for the tags are major
factors in respect of the real update times which can be achieved. The update time
is the acquisition cycle plus transmission time plus processing time.
In order to achieve optimum update times, the following points should be observed
during configuration:
S
Setting acquisition cycles which are too short unnecessarily impairs overall
performance. Set the acquisition cycle to correspond to the modification time of
the process values. The rate of change of temperature of a furnace, for
example, is considerably slower than the acceleration curve of an electric
motor.
Guideline value for the acquisition cycle: Approx. 1 second.
S
In order that changes on the PLC are reliably detected by the TP 070, they must
occur during the actual acquisition cycle at least.
Screens
In the case of screens, the real uptate time which can be achieved is dependent on
the type and quantity of data to be displayed.
In order to achieve rapid update times, only configure short acquisition cycles for
those objects actually need to be updated quickly.
TP070 Equipment Manual
Release03/00
7-5
SIEMENS [ Siemens Semiconductor Group ]
