The default Minimum Frequency 418 or Minimum Percentage 518 extends the pa-
rameterized tolerance band to the hysteresis.
Tolerance band with set minimum frequency
For example, the output variable coming from positive input signals is kept on the
positive min
imum value until the input signal becomes lower than the value for the
tolerance band in the negative direction. Then, the output variable follows the set
characteristic.
15.1.1.4 Filter Time Constant
The time constant of the filter for the analog reference value can be set via the pa-
rameter Filter Time Constant 451.
The time constant indicates the time during which the input signal is averaged by
means of a low pass filter, e.g. in order to eliminate fault effects.
The setting range is between 0 ms and 5000 ms in 15 steps.
451 Function
0 - Time Constant 0 ms
Filter deactivated – analog reference value is
forwarded unfiltered.
Filter activated – averaging of the input signal via
the set value of the filter time constants.
128 - Time Constant 128 ms
256 - Time Constant 256 ms
512 - Time Constant 512 ms
2000 - Time Constant 2000 ms
3000 - Time Constant 3000 ms
4000 - Time Constant 4000 ms
5000 - Time Constant 5000 ms
pos. maximum value
pos. minimum value
neg. minimum value
zero point
tolerance band
neg. maximum value
+10 V
(+20 mA)
(X1/Y1)
(X2/Y2)
06/13 Operating Instructions ACU 175