This section consists of guidelines for using a thermocouple with both internal and external cold junction compensation.
Using Internal Cold Junction Compensation
When measurements are made by thermocouple with cold junction compensation (and only in this case), it is advisable to abide by the following installation rules:
-
PLC must not be directly ventilated, as there must be natural convection,
-
Variations in ambient temperature may not exceed 5°C per hour,
-
Contiguous modules must dissipate between 2.2 W and 3.3 W, which matches the most commonly used modules (TSX P57, TSX DEY 16D2, TSX DEY 32DK, TSX DEY 16FK, TSX DSY 16R5, TSX AEY 414, etc.),
-
The TSX AEY 414 module must be installed in a PLC with a height clearance (D) of a minimum of 150 mm, and a width clearance (d) of 100 mm.
If these guidelines are followed, the module may be installed in the open, in a cabinet or case.
Failure to abide by the above installation guidelines will not prevent the module from functioning. However, the accuracy of the measurements on the configured inputs in the thermocouple range will be altered. In conditions of stable ventilation and with a set configuration, the measurement will simply be offset ny a stable value, for which you will be able to compensate, by proceeding to a "sensor alignment."
See the Map Sensor Alignment for TSX AEY 414
NOTE: Because thermocouple B is not affected by the cold junction compensation of 0 to 70°C, these installation constraints do not apply.
Using External Cold Junction Compensation
The use of a thermocouple with external cold junction compensation requires that the temperature of the cold junction compensation is acquired with a Pt100 class A probe on channel 0 (probe not provided). Channels 1, 2 and 3 of the module can then be used for thermocouple measurement.
In this configuration, there are no particular installation constraints for module TSX AEY 414. The Pt100 probe, however, must be located close to the wiring terminal.
