Rockwell Automation 1756-XXXX ControlLogix Analog I/O Modules - Manual (Page 366)

366 Publication 1756-UM009C-EN-P - December 2010
Appendix E Additional Specification Information
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 used, either:
– -12…30 mV
– -12…78 mV
• Thermocouple type, any of the following:
– B, R, S, E, J, K, N, T, L or D (L and D types can be used with the
1756-IT6I2 only)
• Application temperature (that is, the temperature of the physical
location where the thermocouple is being used)
EXAMPLE
For example, when the 1756-IT6I module is operating in the
following conditions:
• -12…30 mV input range
• connected to a type S thermocouple
• application temperature of 1200 °C (2192 °F)
the module error at 25 °C (77 °F) is +/-1.75 degrees.
In other words, the difference between the temperature the
module reports and the actual application temperature can be
+/- 1.75 degrees.
The module may 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).
IMPORTANT
When determining the thermocouple error, we used a typical
error of 0.05% of temperature range. The error calculations are
listed for each range (that is, -12…30 mV and -12…78 mV) in
the rest of this section.
However, keep in mind that if cold junction compensation is
performed on the thermocouple modules, the cold junction
sensor error values must be added to the +/-1.75 degrees value
in the example above and the numbers listed in the rest of
this section.