A “First-In-First-Out”, or “FIFO” stack is a simple way to organize and keep track of data in a process that is moving and continually changing. A FIFO is simply defined as a set of addresses that hold data.
We will use an integer data file to hold a serial number to be printed on each box. We have created N11 with ten elements, the size of the FIFO stack.
We chose 10 as the size of the FIFO stack because this is the maximum number of boxes that can be queued on the conveyor between the sizing station and the labeling station.
Currently, there is no data in the N11 data file. How will data get placed into the file? It must be loaded into the FIFO stack using a “FIFO Load” instruction.
This instruction is labeled “FFL” and can be found in the “File Shift/Sequencer” tab of the instruction selection window.
When it is time to use the data in the FIFO stack, it is removed from the FIFO stack and copied to another memory address using a “FIFO Unload” instruction.
This instruction is labeled “FFU” and can also be found in the “File Shift/Sequencer” tab.