Customized Characteristic Curve - Siemens SITRANS P DS III Operating Instructions Manual

7.3.5

Customized characteristic curve

Introduction
The customized "characteristic curve" is continuously active as an identical function in the
three following measuring modes "Level", "Flow rate" and "User". This means that the
customized "characteristic curve" always provides a result for the following function, thus
also influencing the measured value status of the affected device variables.
In the device, the characteristic curve vertices are only provided once in the EEPROM.
Therefore, if the measuring mode is changed, you will usually need to adjust the
characteristic curve accordingly.
The characteristic curve function expects at least two and at the most 30 characteristic curve
vertices as input parameters. Characteristic curve vertices are entered in pairs of values
x %;y %. The values for the x-coordinate are only accepted by the device when they run
monotonically. The y-coordinates, on the other hand, may also be non-monotonic. A warning
will however be issued by the configuring device, which you as the user have to recognize
and acknowledge. The output of the characteristic curve is not explicitly stored in a device
variable, but rather is directly interconnected with the input of the next function block in each
case. The pairs of values 0%;0% and 100%;100% are set as default values. In principle,
rising and falling characteristic curves can be configured. With regard to the device variable
status, rising characteristic curves are however preferred. Otherwise the meanings of HIGH
LIMIT and LOW LIMIT are swapped.
See also
Measured value status (Page 116)
SITRANS P DS III with HART
Operating Instructions, 06/2013, A5E00047092-09
Operating functions through HART
7.3 Selecting the measuring modes
109