Siemens SITRANS T Series Operating Instructions Manual page 53

Figure 9-4
Notes on parameter assignment
Be sure to observe the following notes when assigning the parameters for the customer-
specific special characteristic curve. These notes are irrespective of the parameter
assignment software and apply to both device versions of the transmitter.
● The starting point of the characteristic curve correction is:
– The resistance-type transmitter sensor class for the required special resistance
– The mV transmitter sensor class for the required special thermocouple.
The sensor characteristic curve of the resistance-type transmitter or mV transmitter form
the basis (0 to 100%) for the following characteristic curve correction.
● The individual pairs of values must always be specified in the unit % of the set measuring
span.
● The first pair of values is always (X = 0 %; Y = 0 %). The last pair of values is always
(X=100 %; Y=100 %). The first and last pairs of values are specified by the parameter
assignment software and cannot be changed. If a correction of the first and last pair of
values is required, this is only possible by means of a two point trim of the sensor.
● The x-values must rise monotonously when the characteristic curve is input, the y-values
must rise or fall monotonously.
● The x-values do not have to be input in equidistant intervals.
SITRANS TH200/TH300
Operating Instructions, 08/2015, A5E00393069-04
Principle of customer-specific characteristic curve correction
thermometer;
Functions
9.15 Special characteristic curve
53