PLC Input Output Mapping / Buffering | IO Addressing Basics in RSLogix Studio 5000 Allen Bradley

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#1

One of the first tasks of PLC Programming is to properly map Inputs & Outputs. Although this task is fairly straightforward, many programmers either avoid it or implement it incorrectly due to their misunderstanding of it. IO Mapping or Buffering can help you in multiple ways. It allows one to contain all the primary input & output tags within a single program & easily manipulate them as needed. The necessity to manipulate may come from hardware failure or need to upgrade or expand the system. Furthermore, having these assets within a single program greatly reduces the time to troubleshoot and commission new systems.

This is a companion discussion topic for the original entry at https://www.solisplc.com/tutorials/plc-input-output-mapping-buffering-io-addressing-basics-in-rslogix-studio-5000-allen-bradley
#2

This post makes very good points.
I am wondering if you have an opinion on whether the IO routine should be at the Task, Program, or Routine level? My instinct is to call it at the beginning of the periodic MainRoutine.

#3

I’ve always defined it at the start of the cyclic routine. Depending on how you access and what you include in the I/O routine it might make a difference when it comes to the order of execution, but in 99% of scenarios, it shouldn’t really matter at what scope and type of routine you include it in.