Rockwell Automation Publication 1756-UM001M-EN-P - February 2012 149
I/O Modules Chapter 8
Determine When Data is
Updated
ControlLogix controllers update date asynchronously with the execution of logic.
Use this flowchart to determine when a producer, such as a controller, input
module, or bridge module, will send data.
Figure 20 - Data Update Flowchart
Input or Output Data?
Input
Output
COS for Any Point on the Module?
Data is sent to the backplane at the RPI.
Remote or Local?
Analog
No
Yes
Data is sent to the backplane at the RPI and at
the end of every task.
Data is sent to the backplane at the RPI and at
the change of a specified point.
Data is sent to the backplane at the RTS
and RPI.
Data is sent to the backplane at the
RTS.
Analog or Digital?
Analog
Digital
Local
Remote
Digital
• Over a ControlNet network, remote data is sent at the actual packet interval.
• Over an EtherNet/IP network, remote data is usually sent close to the RPI.
Yes
No
RTS ≤ RPI?
Analog or Digital?
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