JUMO 707020 dTRANS T02 PCP - Four-Wire Transmitter Operating Manual - Handbuch (Seite 41)

17
4 Functions and operation
Teach-in
The “Teach-in” parameter serves to define the 0 % value.
During programming, the zero point (e.g. 4mA) is produced at the
output. This value is accepted by pressing the “Zero” push-button
(“Zero” only, not together with “Span”). After a time-out without ac-
ceptance, 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 150
Ω
, with 50
Ω
corresponding to the
valve closed. The range is programmed as follows:
- Potentiometer 50 — 150
Ω
- Output 0 — 20mA
However, because of mechanical tolerances, the potentiometer po-
sition is 52
Ω
with the valve closed, 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 parameter level and select “Teach-in”
(0.4mA should then be present at the output).
- Press the “Zero” push-button – the output must now
change to 0mA.
- Confirm alteration by simultaneously pressing the
“Span” and “Zero” push-buttons.
- Exit the parameter level (either after a time-out of 20sec, or by
pressing “Span and Zero“ again).