Publication 1769-UM002B-EN-P - July 2005
Overview        1-5
General Diagnostic Features
The analog modules contain diagnostic features that can help you identify the 
source of problems that may occur during power-up or during normal channel 
operation. These power-up and channel diagnostics are explained in chapter 6, 
Module Diagnostics and Troubleshooting.
System Overview
The modules communicate to the controller through the bus interface. The 
modules also receive 5 and 24V dc power through the bus interface. The 
1769-IF4, -OF2, -OF8C, and -OF8V modules feature an external 24V dc 
power switch, providing you with the option of using an external power 
supply. See External Power Switch on page 2-10 for details.
You can install as many analog modules as your power supply can support. 
However, the modules have a power supply distance rating of 8, which means 
that they may not be located more than 8 modules away from the system 
power supply.
Figure 1.4 Determine Power Supply Distance
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1123432
234
System Power Supply
Compact I/O
Compact I/O
Compact I/O
End Cap
CompactLogix Controller 
or I/O Communication 
Adapter
Compact I/O
Compact I/O
Compact I/O
OR
 Power Supply Distance
Compact I/O
Compact I/O
Compact I/O
Compact I/O
End Cap
MicroLogix 1500 Controller
with Integrated System
Power Supply
 Power Supply Distance