Allen-Bradley 1756-L6 Series, Reference Manual, Page: 71 / 134

Rockwell Automation Publication 1756-RM001I-EN-P - May 2012 71
FLEX I/O Modules Chapter 6
Wiring the RTD Input Module
In addition to following the Requirements When Using FLEX I/O Analog Input
Modules on page 65 and before wiring the module, consider the following
application guideline:
• RTDs cannot be wired in parallel without severely affecting their accuracy.
Two sensors must be used.
Figure 42 - FLEX I/O Analog RTD Module Wiring
Using Analog Output
Modules
A single analog output module, along with an analog input module for
monitoring is required to achieve SIL 2.
RTD
Input Module
RTD
Input Module
Thermocouple/
RTD/mV
Input Module
Thermocouple/
RTD/mV
Input Module
1794-TB3T 1794-TB3T
1794-TB3G
1794-TB3G
1794-IR8
1794-IR8
1794-IRT8
1794-IRT8
4-wire RTD
3-wire RTD
Two-, three- , or four-wire RTDs can be used as applicable to the associated RTD input module.
IMPORTANT
We strongly recommended that you do not use analog outputs to execute
the safety function that results in a safe state. Analog output modules are
slow to respond to an ESD command and are therefore not recommended
for use ESD output modules.
The use of digital output modules and actuators to achieve the ESD
de-energized state is recommended.
Allen-Bradley Motors