Using The Selectable Input Filter To Provide Noise Rejection - Siemens Simatic S7-200 System Manual

8.2

Using the Selectable Input Filter to Provide Noise Rejection

Some S7-200 CPUs allow you to select an input filter that defines a delay time (selectable
from 0.2 ms to 8.7 ms) for some or all of the local digital input points.(See Appendix A for
information about your particular CPU.) As shown in Figure 8-4, this delay time is added to
the standard response time for groups of four input points. This delay helps to filter noise on
the input wiring that could cause inadvertent changes to the states of the inputs.
The input filter is part of the CPU configuration data that is downloaded and stored in the
CPU memory.
Use the menu command CPU
the delay times for the input filter.
CPU Configure
Port 0
Output Table
Configuration parameters must be downloaded before they take effect.
Figure 8-4
S7-200 Programmable Controller System Manual
C79000-G7076-C230-02
Configure... and click on the Input Filters tab to configure
Retentive Ranges Password
Port 1 Input Filters
I0.0 - I0.3 0.2 ms
I0.4 - I0.7 0.2 ms
I1.0 - I1.3 0.2 ms
I1.4 - I1.5 0.2 ms
Configuring the Input Filters for Rejecting Noise
Input/Output Control
Defaults
OK Cancel
8-5