User's Manual
_________________________________________________________________________
Document #7201-001, Rev B Page 29
5.0 System Description
5.1 Communication System, i-PORT, Tag
Data communication between i-PORT and Tag:
First the i-PORT sends out a scan signal. This signal contains an i-PORT ID and the number
of available slots. All tags that are located in the read zone and that receive the signal
search out a slot at random and answer in this slot. Each slot has a duration of 1.2 ms.
This anti-collision process requires the availability of at least double the number of slots as
the maximum number of tags expected; the probability of collisions increases as the slots
are utilized. As a result of this scan signal, the i-PORT generates a tag list. Data can now
be exchanged (read from or written to) with the tags on this list. Before data is exchanged
with the tag, the i-PORT sends a Session Setup signal to this tag in order to prepare the
tag for the impending interrogation. In contrast to the scan, which addresses all the tags,
all other commands always refer to only one particular tag.