An RFID reader and writer is a device which can read and write to RFID tags. Available in a wide variety of forms, from fixed readers, able to read a number of tags travelling through an entrance (e.g. on a pallet) to Windows based handheld computers with built-in RFID readers. The choice depends on the type of tags being read, the maximum read distance and the environment.
RFID readers are available to scan LF (Low Frequency), HF (High Frequency) and UHF (Ultra High Frequency) RFID tags. LF readers tend to have the shortest read range, but are less affected by metals and water and UHF readers the longest read range (up to 2M with passive tags). Click here for more information on RFID tags.
RFID read writers fall into two main categories, fixed and mobile.
Fixed RFID Read Writers
Fixed readers are mounted permanently in one position or various positions to gain read coverage over an area or location, e.g. a warehouse door, mounted on a conveyor or desk mounted.
Most fixed RFID readers consist of a receiver (similar to a WiFi access point) and separate antennas. This allows maximum flexibility in choosing the type of antenna, which can either be in the form of a portal (tags are read as the pass between two antennas placed either side of an entrance or conveyor) or single antennas with polarisation patterns designed for specific applications (e.g. reading tags at greater distances).
Many fixed readers are UHF because of their superior read distances. For many applications in manufacturing and warehousing it is only necessary to read tags, so many types of device are read only.
The two main types of UHF antenna are:
- Linear polarised where maximum gain is concentrated in a single axis (greatest read range, but the tags must be in the correct orientation)
- Circularly polarised where the gain is uniformly distributed in a radial pattern (shorter read range, but the tags can be read in any orientation).
Fixed RFID readers are also available in HF, e.g. for use in access control.
Mobile RFID Readers
Mobile readers are available in LF, HF and UHF and come in a number of different formats including:
- Corded RFID readers - often powered by the host computer and data is transferred either by a serial or USB interface. Some corded RFID readers look similar to a conventional barcode scanner and work in a similar way.
- Handheld computers - these can either be Windows CE or Windows Mobile based and have built-in RFID readers which can either be LF, HF of UHF.
- Bluetooth RFID Readers - small handheld devices, able to pass data read from a tag to any type of computer, including PDA / cell phones using a Bluetooth interface. Available in HF and UHF formats.
- SD and Compact Flash Readers - small modules that can be plugged into conventional PDAs to provide an RFID capability. Available in LF and HF versions.
- USB Sticks - small modules that can be plugged into a USB port on a laptop or PC. Available in LF, HF and UHF.