Siemens SIMATIC S7 System Manual page 610

Open loop motion control
12.5 Configuring an Axis of Motion
Editing default input and output configuration
To change or view the default configuration of the integrated inputs/outputs select the
required input/output node:
● In the "Active level" field, use the dropdown list to select the active level (High or Low).
When the level is set to High, a logic 1 is read when current is flowing in the input. When
the level is set to Low, a logic 1 is read when there is no current flow in the input. A logic
1 level is always interpreted as meaning the condition is active. The LEDs are illuminated
when current flows in the input, regardless of activation level. (Default = active high)
● In the "System Block", "Digital Inputs" node, you can select the filter time constant (0.20
ms to 12.80 ms) for the STP, RPS, LMT+, LMT-, and TRIG inputs. Increasing the filter
time constant eliminates more noise, but it also slows down the response time to a signal
state change. (Default = 6.4 ms)
● In the "Directional Control" node, you can select the following "Phasing" modes:
– Single phase (2 output)
– Two-phase (2 output)
– AB quadrature phase (2 output)
– Single phase (1 output)
You can also select the "Polarity" (positive or negative) of the outputs.
610
WARNING
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 12.8 ms accumulated duration
before the filter becomes fully responsive to new inputs. During this time, short "0" pulse
events of duration less than 12.8 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.
System Manual, V2.3, 07/2017, A5E03822230-AF
S7-200 SMART