Dancing the TANGO

One of our customers is an administration department at a research center, which is responsible to operate and maintain a synchrotron light source. They are in charge of a whole bunch of “normal” IT infrastructure as well as a wide variety of electronic devices which are used in all kinds of experiment settings. These can be cameras, electronic motors, detectors of all sorts, etc. One of their main day-to-day challenges is to integrate all those devices such that they can be controlled in a uniform way with standard measurement and control tools.

In order to provide a common solution to this task the TANGO platform has been developed in a collaborative effort of some the the main European synchrotron institutes. TANGO is an object-oriented distributed control system in which every device is represented in an abstract way by a so-called Device Server. A device server provides access to a given piece of hardware by exposing its attributes, properties, states, events and supported commands in a uniform way. CORBA is used as middleware which shows that it is still popular in real-time and embedded environments. Device server instances are registered at a central database and can be accessed and controlled using a variety of TANGO tools.

The typical TANGO development process is as follows: Each device comes with some vendor provided driver library and corresponding interface documentation (C interfaces in many cases). Starting with that information, all attributes, states and supported commands are defined using a tool called POGO. The resulting model of the device is then used to generate skeleton code for the device server. Right now, POGO supports C++, Java and Python. Then, the device server skeleton code is completed by accessing the actual device using the driver library.

For example, one of our latest projects was an X-ray detector which is roughly like a CCD camera for X-rays. As such it has read-only TANGO attributes Width and Height which corresponds to the width and height of the CCD chip. Furthermore it has a read-write attribute called ROI (region of interest) which is an array of four integer values (X0, Y0, X1, X2), Exposure Time, an integer value in milliseconds and a variety of other attributes. One obvious TANGO command is Start which tells the camera to start exposure and store resulting images.

So, if you happen to have a synchrotron light source in your garage (or of course any other bunch of hardware that you want to integrate), consider dancing the TANGO.

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