Operation
6.5 Local operation
SITRANS P300 with HART communication
6-14
Operating Instructions, 06/2005, A5E00359579-02
The correlation between the measured pressure and the output current generated is linear.
The following formula can be used to calculate the output current.
,
S
ದ
ದ
P$P$
0$
0(
0$
Figure 6-6
Current calculation formula for setting
I
Output current
MA
actual
Old zero point
p
Pressure
ME
actual
Old limit point
MA
Zero point
MA
target
New zero point
ME
Limit point
ME
target
New limit point
Example of setting with reference pressure
A Initial situation
B Setting zero point
C Setting limit point
0$
0$
0(
0$
0$
0(
S>EDU@
,>P$@
S>EDU@
,>P$@
S>EDU@
,>P$@
DFWXDO
WDUJHW
WDUJHW
DFWXDO
DFWXDO
WDUJHW
Explanations for the example of setting with reference pressure
A The measuring range is from 0 to 16 bar. You are changing the zero point from 0 to 2 bar and the
limit point from 16 to 14 bar. The span is then 12 bar.
B 2 bar process pressure is created.
Use the <MODE> key to switch the transmitter to mode 2. To set the zero point, press the keys
<UP> and <DOWN> simultaneously for 2 seconds.
If there is 2 bar input pressure, the transmitter produces an output current of 4 mA.
C 14 bar process pressure is created.
Use the <MODE> key to switch the transmitter to mode 3. To set the limit point, press the keys
<UP> and <DOWN> simultaneously for 2 seconds.
If there is 14 bar input pressure, the transmitter produces an output current of 20 mA.
D The output current can be calculated for any input pressure using the "current calculation formula
for setting".
