Rockwell Automation 1790D-NOV2/TNOV2 CompactBlock LDX Analog Modules - Manual (Page 14)

Publication 1790-UM001A-EN-P - March 2002
1-4 Overview
General Diagnostic Features
The CompactBlock LDX 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 5, Module Diagnostics
and Troubleshooting.
System Overview The modules communicate to the controller through the DeviceNet
network. Module power is derived from DeviceNet. Additionally, the
analog I/O requires 24V dc field power separate from DeviceNet.
CompactBlock LDX analog bases support up to two discrete LDX
expansion modules.
System Operation
At power-up, the analog base module performs a check of its internal
circuits, memory, and basic functions. During this time, the module
status LED remains off. If no faults are found during power-up
diagnostics, the module status LED is turned on.
After power-up checks are complete, the module waits for valid
channel configuration data. If an invalid configuration is detected, the
module generates a configuration error. Once a channel is properly
configured and enabled, it begins the analog-to-digital or
digital-to-analog conversion process.