Siemens SITRANS TW 7NG3242 Betriebsanleitung Seite 107

• HART communicator Maximum number of parameterizable vertex points = 20
• SIMATIC PDM: Maximum number of parameterizable vertex points = 50
A customer-specific unit can be parameterized for the special characteristic
figure 14, page 107 shows the principle of the customer-specific characteristic
correction
Y values
(special)
Figure 14 Principle of customer-specific characteristic correction
The following notes must be observed for the parameterization of the customer-
specific special characteristic:
• General:
− The number of value pairs must be determined before starting the
characteristic input.
− The X values must increase or decrease monotonously in the characteristic
input.
− The special characteristic linearization type may only be activated when a
valid special characteristic is stored in the device.
− If the type of linearization is set to special characteristic, the default character-
istic unit is '**' in resistance, current and voltage measurement. The default
setting can be changed but the measured values are still displayed with the
default characteristic unit '**'.
• Characteristic input by HART communicator:
− If the characteristic has already been input by SIMATIC PDM and more than
20 value pairs entered, only the first 20 value pairs can be read from the device
with the HART communicator.
− If a special characteristic is to be entered during the offline parameterization,
all device variables must be activated to "Send" in the menu item "1 Select all"
before beginning offline parameterization (menu item "3 Individual process-
ing").
SITRANS TW
A5E00054075-05
Special characteristic Input Resistance (dimension = Ω)
Output Special (dimension = any)
Functions / Operation by HART
Linear interpolation
between the value pairs
value pairs
X1, Y1 : pair 1
X2, Y2 : pair 2
X3, Y3 : pair 3
X9, Y9 : pair 9
X10, Y10 : pair 10
X values
(resistance)
107