Rockwell Automation 1746-NT4 Series B,D17466.6.1 SLC 500 4-Channel Thermocouple/mV Input Module User Manual - Manual (Page 40)

Publication 1746-UM007C-EN-P - July 2004
3-12 Installation and Wiring
Cold Junction Compensation (CJC)
To obtain accurate readings from each of the channels, the cold
junction temperature (temperature at the module’s terminal junction
between the thermocouple wire and the input channel) must be
compensated for. Two cold junction compensating thermistors have
been integrated in the removable terminal block; they must remain
installed to retain accuracy.
In case of accidental removal of either or both of the thermistor
assemblies, make sure to replace them by connecting each one across
the CJC terminals located at the top and bottom left side of the
terminal block. When connecting the thermistor assembly at the top of
the terminal block (between terminals CJC A+ and CJC A-), the lug
containing the thermistor (marked with red epoxy) should attach to
the uppermost screw terminal (CJC A+). When connecting the
thermistor assembly at the bottom of the terminal block (between
terminals CJC B+ and CJC B-), the lug containing the thermistor
should attach to the lowermost screw terminal (CJC B+).
ATTENTION
Do not remove or loosen the cold junction
compensating thermistor assemblies located between
the two upper and lower CJC terminals on the
terminal block. Both thermistor assemblies are
critical to ensure accurate thermocouple input
readings at each channel. The module will not
operate in the thermocouple mode if either assembly
is removed.
CJC Assembly
Thermistor
(Always attach red lug to the
CJC+ terminal.)
Bottom of Terminal Block