Design Guide

Tag Read Meta Data
A DIVISION OF TRIMBLE
84 Functionality of the ThingMagic Nano
Tag Read Meta Data
In addition to the tag EPC ID resulting from ThingMagic Nano inventory operation each
TagReadData (see MercuryAPI for code details) contains meta data about how, where
and when the tag was read. The specific meta data available for each tag read is as
follows:
Meta Data Field Description
Antenna ID
The antenna on with the tag was read. When
Using a Multi-
plexer, if appropriately configured, the Antenna ID entry will
contain the logical antenna port of the tag read. If the same tag
is read on more than one antenna there will be a tag buffer
entry for each antenna on which the tag was read.
Read Count The number of times the same tag was read on the same
antenna (and, optionally, with the same embedded data
value).
Timestamp The time the tag was read, relative to the time the command to
read was issued, in milliseconds. If the Tag Read Meta Data is
not retrieved from the Tag Buffer between read commands
there will be no way to distinguish order of tags read with dif-
ferent read command invocations.
Tag Data When reading an embedded TagOp is specified for a Read-
Plan the TagReadData will contain the first 128 words of data
returned for each tag.
Note: Tags with the same TagID but different Tag Data
can be considered unique and each get a Tag
Buffer entry if set in the reader configuration
parameter /reader/tagReadData/
uniqueByData. By default it is not.
Frequency The frequency on which the tag was read
Tag Phase Not supported in ThingMagic Nano
LQI/RSSI The receive signal strength of the tag response in dBm. For
duplicate entries, the user can decide if the meta data repre-
sents the first time the tag was seen or reflects the meta data
for the highest RSSI seen.
GPIO Status The signal status (High or Low) of all GPIO pins when tag was
read.