VAT 613 Series User Manual

Series 613 INSTALLATION
984360EC Edition 12.08.2022 83/
149
5.13.5 Logarithmic Pressure
To control wide pressure ranges, it is advantageous to control with a logarithmic signal. Note: Only the
PI and the Softpump controller can control with a logarithmic signal. Adaptive controller needs a linear
signal.
Location: CPA/Parameters: Pressure Sensor.General Settings.Logarithmic Pressure
Parameter Description
Upper Limit Value
Highest Value of the logarithmic value.
Corresponds to the sensor full scale defined in the sensor setup.
Percent Per Decade
Defines the logarithmic scale
Lowest Pressure
Defines the lowest pressure that is converted to a logarithmic value.
Corresponds to the smallest valid signal
.
Pressure On Interface
Defines which signal scale is used on the interface.
Linear
Logarithmic
Use Logarithmic Sensor
Set to True to use direct the signal of a logarithmic sensor.
Percent Per
Decade is then not used.
This parameter becomes active only if Pressure Sensor.Sensor
X.Range.Scale
is set to
Logarithmic
Actual Logarithmic Values
Shows the logarithmic value. Full Scale is
Upper Limit Value
EXAMPLE:
Sensor 1 linear 1000Torr, Sensor 2 linear 10Torr
With these sensors the measuring range is: 0.001Torr … 1000Torr, so we cover 6 decades
Percent Per Decade
15
With 15% we cover 6.6 decades (100/15 = 6.6)
Lowest Pressure
0.001Torr (~1mV of Low Sensor)
Upper Limit Value
Shows 1000 (because SFS is 1000)
Actual Logarithmic Value
Example Values
Torr
1000 1000
850 100
700
10
550 1
400 0.1
250
0.01
100 0.001
Pressure On Interface
Linear
We want the logarithmic signal only on the pressure controller but
not on the interface.
Use Logarithmic Sensor
False
Since the sensor signal is linear, there is no possibility to use a
logarithmic signal from the sensor.
Application: Soft Pump
Use of Actual Logarithmic Value in the pressure controller: Set Pressure Control.Controller
X.Control Settings.Pressure Scaler to Logarithmic.
Note: Ramp value use logarithmic signal too, so Ramp.Slope is related to logarithmic scale.
For above example: Slope [Torr] = 15 means 15 of 1000 per Second what is 1.5% what corresponds
to 0.15 Decade per Second.

VAT 613 Series Specifications

General

Brand	VAT
Model	613 Series
Category	Control Unit
Language	English