Rockwell Automation T7420A_AF ICS Regent+Plus Analog Input Modules 60Hz Rejection and Fast Response - Manual (Page 2)

Analog Input Modules (T7420A, AF)
2
Industrial Control Services
prevent the controllers from receiving erroneous data from a
faulty input module.
Three analog input modules can be connected in parallel to
obtain fault tolerant input sensing. In this triple module
configuration, a failed module can be removed and replaced
without interrupting the input signals.
Module Operation
A block diagram of the analog input module is shown in
Figure 1.
Figure 1. Block Diagram of Analog Input Module.
Analog field signals are conditioned and multiplexed into an
analog-to-digital (A to D) converter and converted into 12-bit
digital data. These digital values are stored in the module’s
RAM. The digital logic circuits are optically isolated from the
analog field signals to protect the logic circuits from external
field signal transients and over voltages.