User's Guide

Review Copy 11-6-10
ThingMagic Micro Family User Guide
29
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Tag Read Metadata
In addition to the tag EPC ID resulting from Micro inventory operation each TagReadData (see MercuryAPI
for code details) contains metadata about how, where and when the tag was read. The specific metadata
available for each tag read is as follows:
Tag Read Metadata
Metadata Field
Description
Antenna ID
The antenna on with the tag was 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. When Using a
Multiplexer, if appropriately configured, the Antenna ID entry
will contain the logical antenna port of the tag read.
Read Count
The number of times the tag was read on [Antenna ID].
Timestamp
The time the tag was read, relative to the time the command to
read was issued, in milliseconds. If the Tag Read Metadata is
not retrieved from the Tag Buffer between read commands
there will be no way to distinguish order of tags read with
different read command invocations.
Tag Data
When reading an embedded TagOp is specified for a
ReadPlan 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
Average phase of tag response in degrees (0°-180°).
LQI/RSSI
The receive signal strength of the tag response in dBm.
GPIO Status
The signal status (High or Low) of all GPIO pins when tag was
read.
Gen2 “Q” Value
The value of “Q” indicates the number of slots offered in the
inventory cycle during which the tag was read (2^Q slots with
“Q” from 0 to 15)
Gen2 Backscatter
Link Frequency
250 or 640 kHz
Gen2 Target
“A” or “B”
Power Management
The Micro is designed for power efficiency and offers several different power management modes. The
following power management modes affect the power consumption during different periods of Micro usage
and impact performance in different ways. The available power management modes are:
• Power Modes - set in /reader/powerMode - Controls the power savings when the Micro is idle.