Siemens SIMATIC S7-1500 System Manual page 189

Thus, the rotational speed of the shaft is calculated as follows:
Configuring event/period duration measurement
1. Select the required channel for the Event/period duration measurement operating mode.
Figure 9-27
Inversion
You can invert the 24 V signal to adjust it to your process. By default, the signal is not
inverted.
Input delay
To suppress faults, you can set an input delay of 1 µs or 125 µs for the input filter of the
digital inputs. Changes to the signal are only detected if they are constantly pending for
longer than the set input delay time.
To allow signals pending very briefly to be detected at high counting frequencies, you need
to set an input delay of 1 µs.
When an input delay of 1 µs is set, the use of shielded cables is recommended for optimum
interference immunity.
SIMATIC Drive Controller
System Manual, 11/2023, A5E46600094-AD
Event/period duration measurement
9.9 Configuration of digital inputs/outputs (X142)
Configuring
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