Programming Add-On (AOI) Sequence's

Add On Instructions (AOIs) refers to modules of code which are used repeatedly within a PLC. These can also be known as Function Blocks within some PLCs. An example of when a AOI may be used could be when programming a series of conveyors which are designed to run automatically. The programming for each physical section will be similar (like motor ramping, run-out timers etc) however the inputs and outputs will be different.

A programmer can use a AOI to save time writing specific code for each physical section of conveyor and program a module which can be deployed to multiple sections. This then standardises the functionality across all sections as well as making it easier to manage programming changes. Ideally, each AOI should be programmed in the same way as describe before using sequence programming. However, in some circumstances given the type of function (like indicator stack module) this will not be required.