Rockwell Automation 1794-IRT8XT FLEX I/O Thermocouple/RTD /Millivolt Input Module User Manual - Manual (Page 40)

Publication 1794-6.5.12 - September 2011
28 Read and Write Configuration Maps for the FLEX I/O Module
microprocessor. The filter selections range from Hardware Only to 5 s time
constant. The times are approximate because they are based on the module
scan time, which varies. The default is Hardware Only.
Data Format Selection
This set of bits allows you to select one of these five formats:
• Degree C
• Degree F
• Degree K
• Unipolar – The end points for Unipolar are scaled to the end points of
the thermocouple or RTD range. The default unit
is mV.
• Bipolar – The end points for Bipolar are scaled to the end points of the
thermocouple or RTD range. It uses Ω as default unit.
Options that Affect Each Group of Four Inputs
Sensor Type
This set of bits allows you to select one of nine thermocouple types or one of
eight RTD types. Default unit is mV for thermocouples and ohms for RTDs.
Sensor Mode
This set of bits allows you to select the operational mode for the
thermocouple or RTD inputs. For thermocouple inputs, you can choose the
cold junction compensation mode: internal, external, no CJC and differential
measurement between 2 channels, for example, the value of channel 0 minus
the value of channel 1 appears in the channel 0 and channel 1 data table
locations. For RTD inputs, you can choose 2-wire, 2-wire with user selected
RTD offset, 3-wire, and 4-wire. Default for thermocouples is external CJC;
default for RTDs is 2-wire (with no offsets).
Input Types
This set of bits allows you to select one of two input types: thermocouple
(millivolt) or RTD (resistance). The default input type is thermocouple.
Reference Junction
These bits allow you to select from seven fixed temperatures for the CJC value
that is used by the module in thermocouple mode. Use this mode when the
ambient temperature surrounding the thermocouple connection point is
known and steady. The default temperature is 0 °C (32 °F).