Rockwell Automation 1715-OF8I Redundant I/O System User Manual - Manual (Page 97)

Rockwell Automation Publication 1715-UM001C-EN-P - March 2014 97
Installation Instructions Chapter 2
Field Wiring of Analog Input Termination Assemblies
The termination assembly routes each analog input through a circuit similar to
that shown in Figure 48 . The input channel is protected with a 50 mA fuse.
When an extreme over voltage is applied to the input, the fuse blows. Each analog
input channel is terminated by a precision120 
resistor and fed to the module’s
input circuits. The fuses have a plastic fuse cover that must be kept in the closed
position during normal operation. Standard field wiring connections are made at
the terminal blocks on the termination assembly.
With a simplex termination assembly the input signals are routed to one input
module. In duplex configurations they are routed in parallel to two modules.
Figure 48 - Analog Input Termination Assembly Input Circuit
IMPORTANT These resistors must be considered as part of the field loop circuit. Each channel
has a 50 mA
fuse to prevent component damage in over-current situations.
Input
Circuit
Input
Circuit
Ch. 0…15
+ve
F1 50 mA
100R
2.5V
500mV
0V
20R
-ve
Analog Input Module Termination Assembly
32111-M