FIFO

About this task

A FIFO queue is a named, ordered buffer that a coding scenario can push records into and later get back out in arrival order. Use it to decouple two parts of a process — for example, buffer items scanned at one station and process them, in order, at a downstream station whenever it has capacity. The queue itself only holds a reference to each item; a coding scenario reads or writes it using the FIFO push item, FIFO get item, and FIFO delete item steps (see Coding Scenarios).

Procedure

1. In the side bar, select System Data and click FIFO.
2. Click the add icon to create a new queue.
3. Enter a name for the queue. The name must be unique across all FIFO queues.
4. Select the queue’s type: Product, Production Order, or Logistic Unit. This fixes what kind of record the queue holds.
5. Save the queue.

Results

The queue appears in the FIFO overview, showing its name, type, and current item count (updated live as scenarios push and get items). Opening a queue shows the items currently waiting in it, in position order.

Limitations

• A queue’s name must be unique.
• A queue’s type determines what can be pushed into it — a Logistic Unit queue can only be populated by other means; the FIFO push item scenario step only supports Product and Production Order.
• FIFO queues are global: any coding scenario, on any production line, can push to or get from the same named queue.

What to do next

• Use the queue in a coding scenario — see FIFO Queue for the push/get/delete steps.