AB AOI vs. BRX Subroutine

[RBPLC]

I'm not familiar with Allen Bradley's AOI (Add On Instruction). As I understand it, the BRX subroutine is similar to the Allen Bradley AOI. Can someone who is familiar with AB explain the differences between an AB AOI vs. the BRX Subroutine.

[b_carlton]

The Subroutine in a Do-more is a stand alone chunk of code. In AB the AOI begins as a definition of code and data like a template. When you wish to utilize it a separate instance is created which has its own code and memory space. One instance is distinct from another. Thus the Do-more Subroutine is closer to the AB Subroutine than to its AOI.