Rockwell Automation 1756-XXXX ControlLogix Analog I/O Modules - Manual (Page 130)

130 Publication 1756-UM009C-EN-P - December 2010
Chapter 6 Temperature-measuring Analog Modules (1756-IR6I, 1756-IT6I, and 1756-IT6I2)
To see how to choose a thermocouple sensor type, see page 216 .
Temperature Units
The 1756-IR6I, 1756-IT6I and 1756-IT6I2 modules provide the choice of
working in Celsius or Fahrenheit. This choice affects all channels per module.
To see how to choose temperature units, see page 215 .
Input Signal to User Count Conversion
Integer mode does not support temperature conversion on
temperature-measuring modules. However, this mode can be used by the
1756-IT6I and 1756-IT6I2 modules to calculate user counts for both available
millivolt ranges.
The straight line formulas that can be used to calculate or program a Compute
(CPT) instruction are shown in the table.
For example, if you have 24 mV in the -12…30 mV range, the
user counts = 22498. Counts = -20856 for 2 mV in the 12…78 mV range.
For a table with related values, refer to ControlLogix 1756-IT6I
and 1756-IT6I2 mV Input Signal to User Count Conversion, Knowledgebase
Technical Note ID 41567.
IMPORTANT
The table lists temperature limits for sensors using the
-12…78 mV range only. When the -12…30 mV range is used,
temperature limits are truncated to the temperature value that
corresponds to 30 mV.
Available Range User Count Formula
-12…30 mV y = 1388.4760408167676x-10825.593777483234
where y = counts; x = mV
12…78 mV y = 694.2314015688241x-22244.5904917152
where y = counts; x = mV