The advent of barcoding and sophisticated control software has also played a major part in providing real-time information on the status of each individual item within the handling process.

30 years ago, sorters employed manual coding – product was placed at the start of the sorter and the destination was keyed in from a handwritten label.

Today a barcode can be read using either laser scanners or a vision system. Other forms of package identification: eg: alphanumeric symbols, can be read by using a camera-based vision system.
To keep track of where products are at any given time on a conveyor sortation system, most sorters use window tracking, where a window or space on the belt is generated for each item being sorted.

However, long gone are the days of tracking items by time only, as this frequently led to unacceptable accuracy issues.

Product information is now contained within that window and its progress is closely monitored; problems such as missing products can therefore be identified and subsequent items remain unaffected.
System performance can be further enhanced by the use of variable window lengths, where the size of the window reflects the size of the product within it. A set distance is still maintained between each product.

Fixed windows, where the distance is pre-set, are usually less efficient, but may be appropriate for relatively low throughputs, or where consistently sized items, such as tote boxes, are sorted.
Although a number of new sorter types have been launched in recent years, they still fall into two broad categories – straight line or continuous loop.