Siemens SITRANS P DS III Operating Instructions Manual page 101

Measurement task Linearization symbol
Flow:
Mass/volume flow
without correction
Flow:
Mass/volume flow
with correction
To input a characteristic curve, select the characteristic curve type "user-defined (table)".
Enter the "New number of nodes" which you will later want to enter.
The nodes must always be entered in pairs. For each point x[n] in the working range, a point
y[n] is required.
The device checks which pair of nodes bracket the pressure (secondary variable 1) relative
to the measurement range. To convert the pressure to the measured value (primary
variable), the device interpolates on a line between the interpolation nodes.
SITRANS P DS III/P410 with PROFIBUS PA
Operating Instructions, 02/2016, A5E00053276-08
Operator control functions via PROFIBUS
7.1 Communications structure for PROFIBUS PA
Character- Description
istic curve
type
Root ex- Square root extraction of the input
tracted value for measurement using the ori-
fice plate method.
Additional parameters for the root
function: Application point of the root
function and creep quantity suppres-
sion.
Root ex- Square root extraction of the input
tracted and value for measurement using the ori-
table fice plate method.
With the orifice plate method, the ac-
curacy is greatest when the operating
point is at the design point. If there are
deviations, the measurement deviation
is also greater. For this reason, the
measurement accuracy is corrected
using a characteristic curve with 31
nodes.
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