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FP-TB-1/2/3 Operating Instructions
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the isolation barrier between the I/O modules and the network
module. Figure 12 shows an example configuration with both
separate power supplies and cascading power.
Figure 12.
Example Power Supply Configuration for a FieldPoint Bank
Caution
Cascading power from neighboring bases or
network modules defeats isolation between cascaded
modules.
Thermocouple Wiring
The FP-TC-120 thermocouple input module has the ability to
measure the temperature of the terminals on any of the FieldPoint
terminal bases. This measurement is called the
cold junction
temperature
and indicates the temperature of the junctions
between your thermocouple wire and the screw terminals. This
measurement is used internally by the FP-TC-120 to correct for
the thermoelectric voltages that are generated at these junctions.
Heat dissipated by adjacent modules (or other nearby heat sources)
can cause errors in thermocouple measurements by heating up the
terminals so that they are at a different temperature than the sensor
used to measure the cold junction. The thermal gradient generated
across the terminals can cause the terminals of different channels
FP-TC-120
FP-RLY-420
FP-AO-200
FP-AI-110
Thermocouple
(self powered)
1
2
17
2
Vsup
IN
I
IN
V
COM
1
18 Common
Channel 0
18
2
4-20 mA
±
5V
–
+
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