18 • 750-462 (/xxx-xxx) [2 AI Thermocouple]
Examples of Connection
WAGO-I/O-SYSTEM
750
I/O
Modules
2.1.1.8 Examples of Connection
When connecting the thermocouples, good grounding practices must be
guaranteed between the machine and the sensors that are connected to the
module. Insufficient grounding can lead to common mode voltages, which
may distort the measuring result.
Due to the differential inputs, grounded and ungrounded thermocouples can be
connected in the following ways:
With grounded thermocouples, the common ground (M) can be connected to
the screen (S) using an external bridge so that common mode interferences can
be eliminated (see figure below).
+TC +TC
-TC
-TC
M
M
S
S
+TC
-TC
Fig. 2.1.1-4: Connection of grounded thermocouple
g046204x
With ungrounded thermocouples, the common ground (M) can be connected
both to the TC input and to the screen (S), if required, using an external bridge
so that common mode interferences can be eliminated (see figure below).
+TC +TC
-TC
-TC
M
M
S
S
+TC
-TC
Fig. 2.1.1-5: Connection of ungrounded thermocouple
g046205x
