Special Characteristic - Siemens SITRANS TW 7NG3242 Betriebsanleitung

Functions / Operation by HART
Scaled D/A adjustment:
This transmitter offers the additional option of a scaled adjustment of the analog
output.
Scaled under menu item DA adjustment the values read by the measuring instrument
can be entered directly in SIMATIC PDM or in the HART communicator after entering
the customerspecific scaling (for the example above it applies: lower scaled
adjustmentpoint = 1V, upper scaled adjustment point = 5 V).
A: Output characteristic
B: Characteristic after current transmitter adjustment 4 mA
C: Characteristic after current transmitter adjustment 20 mA
Figure 13 Current transmitter adjustment Example 4 ... 20mA output

4.2.14 Special characteristic

The SITRANS TW offers the option of connecting a large number of sensors to the
device for which a valid sensor characteristic is already stored in the device.
However, there are applications of sensors (e.g. Cu100) for which this device does
not offer correction of a non-linear sensor characteristic as a standard function.
However, in this case it is possible to store a customer-specific special characteristic
in the device.
For the customer-specific characteristic correction, the device requires the value
pairs (X-values, Y-values). These value pairs form vertex points between which the
desired output characteristic is generated by linear interpolation from an input char-
acteristic. The number of vertex points depends here on the parameterization soft-
ware used.
106
→
1.: A B: Parallel shift
→
2.: B C: Change in slope
SITRANS TW
A5E00054075-05