Dectris EIGER 2 - 7 General Usage of the Detector System; Detector Control and Output; Recording an Image or an Image Series

7. GENERAL USAGE OF THE DETECTOR SYSTEM
7.1. Detector Control and Output
The EIGER2 detector system is controlled through the SIMPLON API, an interface to the detector that is based
on the http protocol and implemented on the detector control unit. The API Reference supplied with the
system describes this interface in detail and allows for easy integration of the detector control into the user
instrumentation independent of the operating system or programming language being used. Please refer to
the API Reference for details.
The data recorded by the detector can be accessed in dierent ways. Images can be stored by the lewriter
on the detector control unit as HDF5 les (see chapter 10). HDF5 les include metadata in a NeXus-compatible
format. Buered les have to be regularly fetched and subsequently deleted on the detector control unit as
buer space is limited
1
). Support for reading out multiple thresholds has been introduced in lewriter2. See
the API Reference for further details.
Data can also be fetched through the stream interface, which relies on the ZeroMQ
2
distributed messaging
protocol. The stream has a low latency and oers utmost exibility. The metadata is transferred as part of
the header. Streamed data is not buered and will be lost if not fetched or incompletely fetched. With the
introduction of stream2 it is possible to retrieve the images from multiple thresholds simultaneously at full
frame rates.
Lastly, the monitor interface provides images as raw ti les with minimal metadata. This is a low performance
and low bandwidth interface, which allows to retrieve the latest recorded image for monitoring purposes dur-
ing acquisitions. The monitor oers a relatively small buer. In case of buer overow, the oldest images will
be overwritten. The monitor also allows to retrieve the images from multiple thresholds.
7.2. Recording an Image or an Image Series
Caution #3
Data might have to be fetched concurrently to a running image series. The lifespan of the data
on the detector control unit is dependent on the conguration of your system as well as the
interface used for collecting data. Data not fetched within this lifespan is permanently lost.
To record images or image series, the following steps need to be performed through the SIMPLON API (see
the API Reference for details).
1. Make sure the detector has been set up according to the steps described in chapter 5.
2. Initialize the detector if this has not yet been done. The detector does not need to be reinitialized unless
the detector entered an error status.
3. Set the detector parameters for data acquisition and specify and congure the desired output interface
(le writer and/or stream interface). A list of essential conguration parameters can be found in sec-
tion 7.3.1.
4. Arm the detector
5. Record the image or image series.
• Send trigger(s) to record the image or image series as previously congured.
• Fetch data through the data interface(s).
6. Disarm the detector (to ensure les are nalized and closed).
7. Repeat from step 2 for further data acquisition with dierent settings or to step 3 for identical settings.
1
Buer space varies dependent on the conguration of your system, buer overow will cause loss of data. See API Reference for further
details.
2
ZeroMQ distributed messaging (http://zeromq.org/)
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