Rockwell Automation T3420AF ICS Regent Analog Input Modules - Manual (Page 14)

Analog Input Modules (T3420A, AF)
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Industrial Control Services
transmitters (that require loop power) you will typically need
to connect a 24 VDC power source in the input loop to power
the transmitter and the input loop.
In fault tolerant input applications where redundant analog
input modules interface to single sensors, the analog input
signals connect in parallel across the redundant input
modules. In current input configurations, the three modules
connect in parallel across the single external 250 Ohm
resistor.