Rockwell Automation Allen-Bradley 1790D-N0C2, Руководство пользователя

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Rockwell Automation Publication 1790-UM001B-EN-P - April 2021 11
Chapter 1 Overview
normal channel operation. These power-up and channel diagnostics are
explained in
Module Diagnostics and Troubleshooting on page 41 .
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 I/O 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 indicator
remains off. If no faults are found during power-up diagnostics, the module
status indicator 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.
Module Operation
Input Module
The input module’s input circuitry consists of four analog inputs multiplexed
into one analog-to-digital (A/D) converter. The A/D converter reads the
selected input signal and converts it to a digital value that is presented to the
network. The multiplexer sequentially switches each input channel to the
module’s A/D converter.
Figure 2 shows a block diagram of the circuitry.
Figure 2 - Input Module Circuitry Block Diagram
Isolation
Signal
Control
Data
Microcontroller
Optocouplers
DeviceNet XCVR
Input 0
Select
24V DC
Field
Power Analog
power
supply
Analog
power
A/D
Multiple
xe
r
Input 1
Input 2
Input 3