RSL5000 and add-ons

I have worked with Compact Logix/RSLogix5000 and have not ran into this before. The new equipment shows it has add-ons. I am not at liberty to share the program. I would like to know what add-ons are and used for, please?

Add-on Instructions (AOI) provides a means to encapsulate and possibly protect well tested standardized code. The final product appears as if it were an instruction box with input and output parameters. Unlike parameterized subroutines which may be called from various places each instance is its own set of code which can be monitored, if you allow it.

Let's say you have standarized the code how motor turn on, turn off, monitoring and alarming takes place and typically copy and paste it, changing timer/counter state bits and other assignments with each paste in a new location. All the code can be placed into an Add-on Instruction then utilized with the particular inputs and outputs. Internal aspects like timers and counter will be created in whatever manner they are defined without further action.

Here's a reference.

Thank you Bernie.

In essence an AOI is to code as a UDT is to data. In fact I often pair the two, creating a UDT which holds all the data for a section and an AOI which has the code. Then I pass the UDT based tag for that section to the AOI as an In/Out parameter.