“Digital input” | ModuleIdent 0x2009C8

The binary signal is output via the “Input” process data value.
The digital input module provides the following functions:

• Parameterizable input characteristics (0x80n0:11 “Input Type”)
• Parameterizable filter time (0x80n0:12 “Filter Time”)

Fig.30: Digital input settings

Parameterizable input characteristics

The digital input can be interpreted as having either a positive switching or ground switching characteristic. This is defined at 0x80n0:11 “Input Type” (n = 1 for DI 1, n = 3 for DI 2, n = 5 for DI 3, n = 7 for DI 4):

Sensors with open collector output circuits A sensor with an open collector output circuit corresponds to the “Input Type”: “Ground Switching (NPN)”. In this context, the switching thresholds defined by the manufacturer must be observed to determine whether the input signal should be interpreted as “normally open” or “normally closed”.

Parameterizable filter time

The digital input module provides a parameterizable filter time. This can be used to suppress interference, such as bouncing of a switch signal. Signals with a pulse duration shorter than the set filter time are suppressed.

Filter function sequence

• The filter is enabled on delivery, index 0x80n0:02 “Enable Filter” = TRUE
• The filter is parameterized via index 0x8n0:12 “Filter Time”. The minimum pulse duration depends on the set software filter (see following table).
  Available filter times:

• The filter is disabled by setting index 0x80n0:02 “Enable Filter” = FALSE. In this case, the input signal is only filtered via the hardware. In this case, the filter value is typically 10 µs.