An RFID reader is basically a radio frequency (RF) transmitter and receiver, controlled by a microprocessor or digital signal processor. The reader, using an attached antenna, captures data from tags then passes the data to a computer for processing.

As with tags, readers come in a wide range of sizes and offer different features. Readers can be affixed in a stationary position; for example, beside a conveyor belt in a factory or dock doors in a warehouse, portable (integrated into a mobile computer that also might be used for scanning bar codes), or even embedded in electronic equipment such as print-on-demand label printers.

Features:

RFID readers can communicate at more than one frequency.
RFID readers communicate exclusively with active tags or exclusively with passive tags.
A key feature of an RFID reader is the number of tags that it can sample in its tag population.
Some readers may be able to sample 10 tags a second while others may be able to sample 100 tags a second.
The most common types of communications interfaces on this side of the reader are:

Serial – RS232 or RS422

IP (Ethernet) – TCP or UDP

USB

Some RFID readers support multiple interfaces.
Several RFID reader manufacturers are now offering embedded versions of their readers.
RFID readers can report different types of information.
The reader should report information about the tags it is reading.
RFID readers come in many sizes, frequencies and with different data processing and reporting capabilities.