Basler Electric BE1-851 - Manual (Page 47)

Digital Input Conditioning Function
Status of the contact sensing inputs is checked 24 times per cycle. When operating on a 60 Hz power
system, this results in the input status being sampled every 0.7 milliseconds (0.8 milliseconds on 50 Hz
systems). User settable digital contact recognition and debounce timers condition the signals applied to
the inputs. These parameters can be adjusted to obtain the optimum compromise between speed and
security for a specific application. Digital input conditioning is evaluated every quarter cycle.
If the sampled status of a monitored contact is detected as energized for the recognition time, the logic
variable changes from a de-energized (logic 0 or FALSE) state to an energized (logic 1 or TRUE) state.
Once contact closure is recognized, the logic variable remains in the energized state until the sampled
status of the monitored contact is detected to be open for a period that is longer than the debounce time.
At this point, the logic variable will change from an energized (logic 1 or TRUE) state to a de-energized
(logic 0 or FALSE) state. See Figure 3-4.
Figure 3-4. Digital Input Conditioning Diagram
Setting Up the Digital Input Conditioning Function
The settings for the digital input signal conditioning function and related BESTCOMS features are shown
in Table 3-3. Digital input conditioning settings could be entered using BESTCOMS. Alternately, the
setting may be entered through the communication ports using the SG-IN ASCII command.
Table 3-3. Digital Input Conditioning Settings
Setting Range Increment Unit of Measure Default
Recognition Time 4 to 255 1∗ Milliseconds 4
Debounce Time 4 to 255 1∗ Milliseconds 16
Time Units
Pull-down menu that selects the unit of measure for Recognition Time and
Debounce Time. Units of measure available are: milliseconds, seconds, minutes,
and cycles. The default is milliseconds.
Name
User programmable label for the input contact. Used by the reporting function to
give meaningful identification to the input contact. This label may be up to 10
characters long.
Energized State
User programmable label for the contact’s energized state. It is used by the
reporting function to give meaningful identification to the state of the input
contact. This label may be up to seven characters long.
De-Energized State
User programmable label for the contact’s de-energized state. It is used by the
reporting function to give meaningful identification to the state of the input
contact. This label may be up to seven characters long.
∗ Since the input conditioning function is evaluated every quarter cycle, the setting is internally rounded to
the nearest multiple of 4.16 milliseconds (60 Hz systems) or 5 milliseconds (50 Hz systems).
9289900990 Rev R BE1-851 Input and Output Functions 3-5