Although it is helpful, for understanding Continuous Mode in general, to compare
CONFIG-START on a normal tag with READ on a CM tag, the following listing gives
aspects that are NOT analogous (besides the obvious difference of one being a
START event and the other a READ event).
In READ events with Continuous Mode (“CM”) tags:
•
The configuration parameters on the TagMate USB
®
are not actually written
to the tag. They are only transferred to the tag’s data record inside the
TagMate USB
®
, as if they had been read from the tag.
•
The log interval from the stored configuration is replaced by the log interval
read from the tag.
•
The log delay from the stored configuration, if any, is replaced with zero.
•
The initial shelf life from the stored configuration is used for shelf life
calculation as usual, but also to determine the maximum time span of data
read from the tag, working backwards from the most recent. This limit may
dictate that less than the tag’s 702 data point capacity will be read, even
though 702 data points are available.
•
The Info Field is given a prefix of “CM-” as an indicator for Continuous Mode.
The last three characters of the Info Field are therefore lost.
As described above under “Tag START Operations”, the TagMate USB
®
acquires its
configuration parameters and Info field from a TagMate
®
Configuration Tag. In
multi-configuration situations, it is adviseable to pre-read the appropriate TagMate
®
Configuration Tag whenever reading CM tags, ensuring that the desired configuration
is applied.
Data Outputs in Continuous Mode
The retrieved data set is limited by the initial shelf life configuration setting as
described above, or the 702 data point limit, or the total data points on the tag.
READ alarms can result for CM tags as for normal mode tags, and the tag data file
will be generated as usual from the retrieved data set. However, in order to avoid
false alarms or misleading summary data resulting from looking too far back into the
data buffer on a CM tag, alarm
calculations
are
disabled
until a temperature
reading is encountered that falls inside the Tmin–Tmax temperature range, or until
80% of the total data set has been processed, whichever event comes first.
This aspect of CM tags enables users to create start “events” merely by a change in
the environment of the tag---moving the tag from outside to inside the Tmin-Tmax
range as it is used for monitoring.
TagMateUSB Aug 11, 2009
Page 17 of 20