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Logic functions | Limit value switch
11.6
Limit value switch
The limit value switch works with an input whose data format can be configured, and
with a 1-bit output to output the result of the threshold evaluation. The limit value
switch compares the value received at the input with two configurable hysteresis
threshold values. Once the upper threshold value (H2) is reached or exceeded, the
output can transmit a switching telegram (e.g. ON = true). If the value falls below the
lower threshold value (H1), the output can transmit another switching telegram (e.g.
OFF = false).
The switching telegrams can always be configured in the ETS when the threshold
values a re exceeded and undershot.
The two threshold values d efine a hysteresis. The hysteresis prevents frequent
switching back and forth of the output, provided that the input value changes continu-
ously in small intervals. Only when the change in value at the input exceeds the hys-
teresis as a whole, does the output switch the status.
Image 49: Example of a hysteresis evaluation by upper and lower threshold value
The two threshold values c an be freely configured in the ETS. Make sure that
the upper threshold value is greater than the lower one!
Heating actuator 6-gang with controller | Order no. 2139 00 | 21393100
Image 48: Limit value switch
Page 245 of 257
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