Thermocouple error – Rockwell Automation 1756-OF8I ControlLogix Eight-channel Isolated Analog I/O Modules  User Manual

Page 41

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Rockwell Automation Publication 1756-UM540A-EN-P - May 2014

41

ControlLogix Isolated Analog I/O Module Features

Chapter 2

Thermocouple Error

Thermocouple error at 25 °C (77 °F) indicates the module’s accuracy in
measuring temperature. This accuracy varies depending on these factors:

Input range = -100…100 mV.

Thermocouple sensor type, any of the following:

Type B

Type C

Type D

Type E

Type J

Type K (default value)

Type N

Type R

Type S

Type T

Type TXK/XK (L)

Application temperature, that is, the temperature of the physical location
where the thermocouple is being used.

EXAMPLE

When a 1756-IRT8I module is used with a thermocouple input type in the
following conditions, module error at 25 °C (77 °F) is ±3.74 °:

Connected to a type S thermocouple

Application temperature of 1200 °C (2192 °F

)

In other words, the difference between the temperature the module
reports and the actual application temperature can be ±3.74 °.

The module can report an application temperature of 1200 ° C (2192 °F

) in

this case when the actual temperature can be in the range from
1196.26…1203.74 °C (2185.268…2198.732 °F

).

These calculations used a typical error of 0.02% of full scale range.

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