ThingMagic Mercury API v1.23.0 - Manual (Page 26)

Reading Tags - The Basics
26 Level 1 API
 duration - The number of milliseconds to read for. In general, especially with
readers of type SerialReader , the duration should be kept short (a few seconds) to
avoid filling up the tag buffer. Maximum value is 65535 (65 seconds).
It performs the operation synchronously, and then returns an array of TagReadData
objects resulting from the search. If no tags were found then the array will be empty; this
is not an error condition.
When performing a synchronous read() operation the tags being read are buffered on the
reader and stored in the reader’s Tag Buffer. During a single read() operation tag de-
duplication will occur on the reader so re-reads of the same tag will result in the tag’s
ReadCount metadata field to be incremented, a new
TagReadData instance will not be
created for each. The reader specific hardware guide should be referenced for
information on the size of the Tag Buffer.
Note
The C-API read() implementation takes 3 arguments, reader pointer,
duration in milliseconds and the reference to the tag count. The third
parameter is an output parameter which gets filled by the read() method.
Upon successful completion of read() the method returns TMR_SUCCESS
status with the number of tags found. The
C Read Iterator methods need to be
used to retrieve the tags.
Reader.startReading()
The startReading() method is an asynchronous reading method. It does not take a
parameter.
void Reader.startReading()
It returns immediately to the calling thread and begins a sequence of reads or a
continuous read, depending on the reader, in a separate thread. The reading behavior is
controlled by the
Reader Configuration Parameters :

/reader/read/asyncOnTime - sets duration of those reads,

/reader/read/asyncOffTime - sets the delay between the reads.
The results of each read is passed to the application via the ReadListener interface; each
listener registered with the addReadListener() method is called with a TagReadData
object for each read that has occurred. In the event of an error during these reads, the
ReadExceptionListener interface is used, and each listener registered with the
addReadExceptionListener() method is called with a ReaderException
argument.
The reads are repeated until the stopReading() method is called.