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L-14
3 Wiring
3.4 Selection of the Thermocouple
FX
3G
/FX
3U
/FX
3UC
PLC User's Manual - Analog Control Edition
FX3U-4AD-TC-ADP (4-channel Thermocouple Data Input)
3.4 Selection of the Thermocouple
3.4.1 Thermocouple type
• There are 2 types of thermocouples: K type and J type. When selecting the thermocouple type, make sure
that the same type of thermocouple is connection to all the channels.
• Be sure to use a non-grounded thermocouple type.
3.4.2 Compensating lead wire
To connect the thermocouple, use one of the following types of compensating lead wires:
• The compensating lead wire indicates a temperature value of approximately 0.12
°
C higher than that of the
wire resistor (10Ω). Use the appropriate compensating lead wire when considering this difference.
• If the compensating lead wire is very long, the wire may be easily affected by noise, etc. It is, therefore,
recommended for the length of the compensating lead wire to be 100 m or less.
3.5 Wiring of Thermocouple
Wiring depends on the thermocouple type selected. Refer to the following wiring diagrams:
3.5.1 Wiring of thermocouple type K
*1. It is not necessary to connect lines to the J-type terminals. Leave these terminals disconnected.
*2. Keep the thermocouple away from inductive noise (commercial power, etc.).
Thermocouple Type of compensating lead wire
Type K KX,KCA,KCB,KCC
Type J JX
3k
Ω
ch
TC-ADP
Class-D
grounding
+5V
L
+
L
-
24+
24-
Compensating
lead wire
Terminal block
24V DC
L
+, L
-, ch
:
represents the channel number.
Type J
Type J
Thermocouple
type K
*2
ch
L
+
L
-
3k
Ω
Temperature
compensating circuit
Temperature
compensating circuit
Shield
OPEN*1