Endress+Hauser Liquistation CSF34 - Page 137

Liquistation CSF34 Operation
Endress+Hauser 137
10.6.5 Mathematical functions
In addition to "real" process values, which are provided by connected physical sensors or
analog inputs, mathematical functions can be used to calculate a maximum of 8 "virtual"
process values.
The "virtual" process values can be:
• Output via a current output or a fieldbus
• Used as a controlled variable
• Assigned as a measured variable to a limit switch
• Used as a measured variable to trigger cleaning
• Displayed in user-defined measuring menus
Difference
You can subtract the measured values of two sensors and use the result to detect incorrect
measurements, for example.
To calculate a difference, you must use two measured values with the same engineering
unit.
Menu/Setup/Additional functions/Mathematical functions/MF1 to 8/Mode = Difference
Function Options Info
Calculation Selection
• Off
• On
Factory setting
Off
On/off switch for the function
Y1 The options depend on the
sensors connected
Select the sensors and measured variables that
should function as the minuend (Y1) or
subtrahend (Y2).
Measured value
Y2
Measured value
Difference value Read only View this value in a user-defined measuring
screen or output the value via the current output.
Mathematical function
assignment view
Overview of the configured functions
Redundancy
Use this function to monitor two or three sensors with redundant measurements. The
arithmetic average of the two closest measured values is calculated and output as the
redundancy value.
Menu/Setup/Additional functions/Mathematical functions/MF1 to 8/Mode = Redundancy
Function Options Info
Calculation Selection
• Off
• On
Factory setting
Off
On/off switch for the function
Y1 The options depend on the
sensors connected
You can select a maximum of 3 different types of
sensor that output the same measured value.
Example for temperature redundancy
You have a pH sensor and an oxygen sensor at
inputs 1 and 2. Select the pH sensor as Y1 and
the oxygen sensor as Y2. Measured value: Select
Temperature in each case.
Measured value
Y2
Measured value
Y3 (optional)
Measured value