User's Manual

DF RFID PROXIMITY RW READER USER MANUAL V1_05.DOC PAGE 11 OF 23
6. Operations overview
The reader transmits CW carriers, which causes the tags in the RF beam to power up and start
backscattering their ID codes back to the reader. The RF unit receives the modulated backscatter
and decodes the tag ID’s. A time stamp is typically added by the reader for each tag read event
(Wiegand mode is 26-Bit ID only). The data from the reader is transmitted immediately
communication port to the host. No buffering takes place on the reader. When using the USB or RS
422 interface, additional data fields can be added. If more ID’s are received from the same tag
before its packet had been transmitted, a hit counter is increased. These hit counts are included in
the transmitted packet as “I” counts. The length of the tag ID data packet that is sent to the host
can be altered. The USB and RS422 readers can be used to WRITE USER DATA into EM4522 tags and
also setup these tags to operate in TTO mode. (TTO is a special operational mode of the tag in
which the tag will send its USER DATA pages in the presence of a RO or Non-modulating reader)
Refer to the instruction set in the serial protocol document or Showtags document – www.ipico.com.
7. Application notes
a. Read distances depends on the relationships between Tag size and Antenna
characteristics.
b. Electrical noise sources in close proximity to the reader may influence read performance. The
magnetic field produced by the unit may also cause slight interference with other sensitive
electronic equipment.
c. The USB interface allows the reader to be powered from the host as well as for bi-directional
communication between the host and the reader. An alternative isolated RS422 interface is
also available for integration into industrial point-to-point control applications. The reader is
typically used as a desktop registration reader, validation reader, printer programming head
or production line programming head, depending on how it integrates into the host
application.