Festo CPX−Terminal Instrucciones De Instalación página 23

Cold junction compensation (only for CPX−4AE−TC)
Cold junction compensation is required for precise
measurement using thermocouplers (TC), so that the abso
lute temperature at the measuring point can be recorded
exactly. Cold junction compensation eliminates the influ
ence of the ambient temperature, especially in the environ
ment of the plug connector and the connection block.
Note
The CPX−4EA−TC module has internal cold junction com
pensation that ensures sufficient accuracy of measure
ment in certain applications.
The internal cold junction compensation is fixed at a
constant ambient temperature of 25°C. If the actual
ambient temperature of the module deviates from this
reference value, the internal cold junction compensa
tion has a negative impact on the accuracy of the
measured values.
You can select between internal and external cold junc
tion compensation by setting a parameter.
External cold junction compensation is always prefer
able to internal cold junction compensation. For it, you
require a Pt−1000 resistor for each input. You can order
it from Festo as an individual part (part no. TN 553 596).
The Pt−1000 resistor must be mounted directly next to
the point of connection (in the plug or at the terminal).
Observe additional notes on applications and mounting
in the description of the CPX analogue I/O module
(P.BE−CPX−AX−...).
Festo CPX−AX 0811c English 23