Siemens S7-1200 System Manual page 145

The default filter time for the digital inputs is 6.4 ms. You can choose any of the following
filter time values:
• 0.1 us
• 0.2 us
• 0.4 us
• 0.8 us
• 1.6 us
• 3.2 us
• 6.4 us
• 10.0 us
• 12.8 us
• 20.0 us
Risks with changes to filter time for digital input channel
If the filter time for a digital input channel is changed from a previous setting, a new "0"
level input value may need to be presented for up to 20.0 ms accumulated duration before
the filter becomes fully responsive to new inputs. During this time, short "0" pulse events of
duration less than 20.0 ms may not be detected or counted.
This changing of filter times can result in unexpected machine or process operation, which
may cause death or serious injury to personnel, and/or damage to equipment.
To ensure that a new filter time goes immediately into effect, a power cycle of the CPU
must be applied.
S7-1200 Programmable controller
System Manual, 03/2014, A5E02486680-AG
• 0.05 ms
• 0.1 ms
• 0.2 ms
• 0.4 ms
• 0.8 ms
• 1.6 ms
• 3.2 ms
• 6.4 ms
• 10.0 ms
• 12.8 ms
• 20.0 ms
WARNING
Device configuration
5.5 Configuring the operation of the CPU
145