Siemens SIMATIC S7 - Page 25

Operation
2–23
IP244
C79000–B8576–C859–02
The bridge circuit is balanced in the factory to 0 C = 0 mV. When using a 3-core shielded
connecting cable with 3 x 1.5 mm
2
cross sectional area, the balancing error over 50 m of cable
is < 1.5 C.
Fig. 3.1.3/2  Connecting a resistance thermometer for reference junction temperature compensation
0 V
M+
Pt 100
-
+
-
+
Multiplexer
17
M-
35
U
ref
16
0 V, MĆbar
in cabinet
(reference potential)
IP 244
The cable from the Pt 100 to pin 16 must be connected and must not be grounded
(otherwise this results in a ground loop, falsifying results).