Siemens NCU 7x0.3 PN Series Manual page 134

Connectable components
9.3 PP 72/48D 2/2A PN
Measurements with 4-wire connections compensate for line resistances and return a
considerably higher degree of precision in comparison with 2-wire connections.
x
ADU
I
c
Figure 9-19
Measurement using a 3-wire connection system
The following pins must be jumpered at connector X3 in order to perform the measurement
in the PT100 using a 3-wire connection system:
● Temperature measurement with channel 1:
● Temperature measurement with channel 2:
Note
Measuring accuracy
The accuracy of the temperature input becomes poorer: The resistance of the connecting
cable of the jumpered connecting cable falsifies the measurement.
134
1, 2
Analog Digital Unit
Constant current
PT100 pin assignment
Short-circuit pin 2 (CI 1) and pin 4 (AI 1-) and connect the jumper at connector X3
Short-circuit pin 6 (CI 2) and pin 8 (AI 2-) and connect the jumper at connector X3.
NCU 7x0.3 PN
Manual, 09/2011, 6FC5397-1EP40-0BA0