4.4 Adjusting the position
transmitter
Note: The starting point (zero) and upper
range value (span) must be set before cali
-
brating the position transmitter.
Depending on the position of the 4-pin plug
(symbol on plug: >> or <>), the feedback
signal can be set to either a range of 4 to
20 mA or 20 to 4 mA for 0 to 100 % travel.
Zero point (ZERO)
Use the switches 1 and 2 to preset the zero
point and the ZERO potentiometer for
fine-tuning. The adjusted value always refers
to 4 mA.
Span (SPAN)
Use the switches 3 and 4 to preset the span,
i.e. the upper range value, and the SPAN
potentiometer for fine-tuning. The adjusted
value always refers to 20 mA.
Example:
Move the valve to open position while ob
-
serving the position transmitter signal.
If the signal does not move in the desired di-
rection, switch over the multi-pin plug.
Adjust the zero point (4 mA) and span
(20 mA) for the valve positions according to
Table 10.
38 EB 8355-1 EN
Operation
Table 10 Position transmitter
Valve movement Transmitter signal Direction of signal Set zero/span to
OPEN
CLOSED
Current increases
OK
20 mA
4 mA
Valve OPEN
Valve CLOSED
Not OK
Change plug
4 mA
20 mA
Valve OPEN
Valve CLOSED
Current drops
¯
OK
4 mA
20 mA
Valve OPEN
Valve CLOSED
Not OK
Change plug
20 mA
4 mA
Valve OPEN
Valve CLOSED
ZERO
SPAN
12 34
SPAN
ZERO
Fig. 15 · Position transmitter
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