The writing process, called flux reversal, causes a change in the magnetic field that can be detected by the magnetic stripe reader. Information is written on the stripe by magnetizing the tiny bars in either a north or south pole direction with a special electromagnetic writer, called an encoder.

When all the bar magnets are polarized in the same direction, the magnetic stripe is blank. Each magnetic particle in the stripe is a tiny bar magnet about 20-millionths of an inch long. The magnetic stripe on the back of a badge is composed of iron-based magnetic particles encased in plastic-like tape. Swipe readers require that the badge pass completely through the reader. For instance, insertion readers require that the badge be inserted into the reader and then pulled out. Magnetic stripe readers can be read by a computer program through a serial port, USB connection, or keyboard wedge, and are generally categorized by the way they read a badge. A magnetic stripe reader, also called a magstripe reader, is a hardware device that reads the information encoded in the magnetic stripe located on the back of a plastic badge.

Magnetic stripe card encoder software