20
4 Functions and operation
Teach-in
The “Teach-in” parameter serves to define the 0% value. The actual
value that is present at the output will become a 0% value through
“Teach-in” programming.
This value is accepted by pressing the d or i button and executed
with q. After a time-out without acceptance, the old value will be
available again.
Example:
The position of a valve is detected by a potentiometer. The potenti-
ometer covers the range 50 to 150Ω, with 50Ω corresponding to the
valve closed. The range is programmed as follows:
-potentiometer 50—150 Ω
-output 0—20mA
Assumption:
However, because of mechanical tolerances, the potentiometer po-
sition with the valve closed is 52Ω, which results in an output cur-
rent of 0.4mA. Thanks to the “Teach-in” function, this error can be
eliminated as described below:
-close valve
-call the parameter level and select OFFS
(0.4mA should then be present at the output).
- press the d or i button – the output must now
change to 0mA.
-confirm alteration by pressing q.
-exit the parameter level (either after a time-out of 20sec or by
simultaneously pressing q + d.
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