Rockwell Automation T3431-CA ICS Regent Thermo Couple Input Assembly - Manual (Page 21)

Thermocouple Input Assembly (T3431)
P D - 6 0 2 4 M a r - 0 6
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used in the application program to represent the value of
the thermocouple input in your control algorithms and
interlocks. The input data is in the units and format as
configured on the thermocouple Mux. For more
information, see Thermocouple Multiplexer Configuration,
starting on page 12.
Figure 13. Defining a Thermocouple Input Point.
Programming
Inputs are referenced in the application program through the
tag names defined in the I/O Configuration Editor. The
thermocouple inputs variables will be in the engineering units
(degrees F or C) and resolution (1 or 0.1 degree) as configured
on the thermocouple multiplexer. Because the input data is
already represented in engineering units, there is no need to
scale the thermocouple input variables in the application
program.
Note: The MSB of each thermocouple input represents out-of-
range (or NOSIG) status. This bit is normally equal to one.
When thermocouple inputs are used in application program
instructions, this MSB is masked and the sign bit is shifted to
the MSB. This allows the application program instructions to
evaluate only the data portion of the temperature value. This
is true for all application program instructions except Block
Move (in ladder logic). The Block Move instruction moves the
entire word of data without masking off the NOSIG bit.