This tip is pretty straightforward and simple, but one that I commonly see missing from programs in the field. When you're writing your program for a PLC use a input and output folder to map physical I/O into software I/O. This is done by creating a program folder or equivalent sorting method in the software program and putting all of your I/O into this folder.
As you can see here, we have a program folder labeled 'Input Map' and another labeled 'Output Map'. These two program folders contain all of the data for our mapping to the real world PLC inputs and outputs. When creating our mapping we simply take our real word I/O and tie it to a software memory, or tag location in the PLC.
IO Mapping is a simple practice to implement. It allows a PLC programmer to set up a routine which contains all the inputs & outputs for a given system. This translates to easier commission of the system, faster troubleshooting & easier fixes if the problem is determined to be one of the points of IO. When modifying the physical inputs and outputs it's very simple and quick to modify one rung of code and be up and running in minutes rather than having to sort through hundreds of rungs looking for every location the I/O point is used.
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