
with appropriate parameters. Only then will you be given a meaningful measured value for the
three device variables.
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DV Device variable
MA Start of scale value
ME Full scale value
Figure 7-2 Measuring mode "Level"
Functions of the "Level" block
The first function, "Input scaling, pressure", sets the pressure range used by the following
functions in all three blocks in the same way. Ideally, this range corresponds to the sensor
limits of the transmitter. In the following calculation examples, 0 and 4 bar are assumed for
these sensor limits for all blocks. You can however also set a downscaling, e.g. 1:2. The
downscaling
of 1:2 means that 50% of the rated measuring range, here 2 bar, can control the
following characteristic curve 100%.
Use the "Output scaling, level" to set the measuring limits for the measuring mode "Level" with
a unit from the level range. Parameter settings in this example are 10 and 20 m. At 0 bar
process pressure, 10 m is displayed in DV4 and 20 m is displayed at 2 bar. The values for the
start of scale value and the full scale value, which are effective for the analog output, are
configured in the "analog output" block.
In the calculation example, the two pairs of values 0%;0% and 100%;100% are configured for
the customized "characteristic curve". This is the default setting. The measured value from the
pressure scaling is transferred 1:1 in this example.
Operating functions through HART
7.3 Selecting the measuring modes
SITRANS P, DS III series with HART
104 Operating Instructions, 09/2012, A5E00047092-08
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