Pressure

Pressure switches
Electronic pressure switches / pressure transmitters PST, PST…-R / Smart Press
13
Settings at user level
Switch output OUT 1 and OUT 2
At user level, the switching point (SP) and reset point (RP) can be set across the entire nominal pressure
range.
When the DIG (digital incremental sensor) is turned by one notch in the clockwise direction, the symbol
“OUT 1” and “SP” appears. When the DIG is pressed, the EDIT “symbol” appears.
After that, any switching point can be selected by turning the DIG clockwise or anticlockwise. When
you press the DIG again, “SAVE” is displayed. Press the DIG again to confirm. The chosen switching
point is now permanently saved.
Turn it clockwise again to display the reset point (RP) symbol. The reset point (RP) is set in the same
way as the switching point (SP).
Analogue output (AOUT)
Turning the DIG clockwise again opens the analogue output (AOUT) window. The screen displays the
lower pressure value set (AOUT ZERO). Press the DIG to enter “EDIT” mode and then “SAVE” to save
the lower reference value permanently.
Turn the DIG again to set “AOUT” “FSO”. Here you can alter the upper reference value. The pressure
value can be changed in the way described above.
Pressure
without filter
setting
with filter
setting
Time
Filter setting (attenuation)
To make the pressure switch insensitive to pressure peaks and to avoid distorting the measured value
due to pressure peaks, a filter value of 0…95% can be set. After setting the switching points of
OUT 2, turn the DIG again to open the “ATT” window. After pressing the DIG the user can change the
value in edit mode (EDIT) or turn the filter off completely (OFF). Save the selected filter value with
“SAVE”. It is now permanently stored in the memory. The currently measured pressure is compared
with the pressure measured previously. The currently measured pressure is then attenuated depending
on the selected degree of filtering. This attenuation affects all outputs, i. e. all open collector outputs
and relay outputs as well as the analogue output, as the attenuation has a direct influence on the
incoming sensor signal. The previously measured pressure and the currently measured pressure (internally
offset against each other) always produce a weight of 100%. The filter attenuation (effect) can be
mathematically expressed as follows:
R[x] = M[x] * (100% - F) + R[x - 1] * F
where:
“F” is the selected attenuation in %,
“M[x]” is the measured value as a function of a defined time “x”,
“R[x - 1]” is the previously displayed and output (calculated) measured value “x - 1”, and
“R[x]” is the displayed and output (calculated) measured value in the time “x”.
Electronic slave pointer
Before you exit user mode, the Smart Press shows the extreme states in the past by means of
right/left bar graph arrows and maximum values in the vacuum/overpressure range. Press DIG
once to enter “EDIT” mode and turn the knob to see how much time has passed since the event
occurred.