Rockwell Automation 1794-IRT8XT FLEX I/O Thermocouple/RTD /Millivolt Input Module User Manual - Manual (Page 20)

Publication 1794-6.5.12 - September 2011
8 Install Your FLEX I/O Input Module
Series A and Series B
The table, Series A and Series B Differences, describes the differences between
Series A and Series B of the FLEX I/O Thermocouple, RTD, and mV Input
modules.
Power Requirements The wiring of the terminal base unit is determined by the current draw
through the terminal base. Make certain that the current draw does not
exceed 10 A.
Series A and Series B Differences
Mode 1794-IRT8 Series A 1794-IRT8, 1794-IRT8XT
Series B
Isolation Between user side and
system side
Between user 24V DC and
user I/O; between user side
and system side
Common Mode Range +4V DC +15V DC
Thermocouple Mode
Wire-off Detection
When an open sensor is
detected, data defaults to
maximum
value
When open sensor is
detected, data defaults to
minimum
value
ATTENTION
In the RSLogix 5000 software, if using a series B product to replace a
series A product, the module will be accepted without an electronic
key mismatch warning.
This is true for 1794-IRT8 and 1794-IRT8XT modules installed on
Ethernet/IP, ControlNet, or Remote I/O networks.
ATTENTION
The CJC Status bit, Read Word 9, Bit 3 is added with the Firmware C
release of the 1794-IRT8 Series B module.
The CJC Status bit is turned On when the temperature between the
CJCs is greater than 6 °C but less than 12 °C.
When this temperature difference is above 12 °C, then the CJC Alarm
bits are set.
Also, if a CJC temperrature is over-range or under-range, then the
associated CJC Alarm bit is set. In this condition, the CJC Status bit is
not set.
The CJC Status bit did not exist in Series A.
ATTENTION
Total current draw through the terminal base unit is limited to 10 A.
Separate power connections may be necessary.