Software Filters; Filter On Range - Siemens SIMATIC 505 User & Programmers Manual

5.3

Software Filters

5.3.1

Filter on Range

5-8 Selected Functions
The TurboPlastic module provides several distinct user-selectable software
filters to allow operation in spite of noisy input signals. These filters are
provided for use when ambient noise is slightly above normal and when
random spikes on the input might occur. These filters are not effective for
noise levels substantially above recommended levels.
A ranging filter is provided for use when random spikes may be present on
the input. This filter computes the difference between the current position
reading and the last position reading and compares this value to the
velocity scaling factor (VSF) that has been entered for the profile.
If the difference is less than the VSF, the value is used as read.
If the difference is greater than the VSF, the value is accumulated into
an averaging register, and another reading is requested from the analog
input.
This process is repeated until a valid reading is obtained or the maximum
number of 10 reads has been reached. At that time the average is used in
the velocity calculation and the module continues its normal scan operation.
Since the TurboPlastic module can complete an analog input read in about
25 microseconds, a number of reads can be allowed in the same scan
without substantially affecting the over-all module performance.