How much control do you need to dance TANGO?

This set of slides introduce the TANGO control system for the SKA telescopes, using analogies between tango dancing and the paradigms of the TANGO control system.

The talk was given in the context of the Engineering Q&A talks of the SKA Organisation.

Transcript

1. How much control do you
   need to dance TANGO?
   Juande Santander-Vela
   SDP/TM Element Systems Engineer
   

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2. TANGO: SCADA for SKA
   SCADA: Supervisory Control And Data Acquisition
   TANGO: TAco Next Generation Object-oriented
   (control system)
   ➥ TACO: Telescope and Accelerator Control Objects
   Not that foreign
   to astronomy!
   

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3. TACO @ Hartebeesthoek Radio
   Astronomy Observatory
   

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6. Why TANGO for SKA?
   Need for a common control middleware across the SKA
   Need for industrial-strength SCADA
   Open Source, very large, vibrant community
   Some experience in astronomy: TANGO is TACO++
   Preferred to ALMA Common Software & EPICS
   Very successful in
   synchrotron world
   

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7. How do you TANGO?
   The TANGO Control System Manual
   Version 9.2
   

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8. The TANGO Control System Manual
   Version 9.2
   RTFM!
   Looks easy!
   

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9. Tango & Control
   There’s a leader
   There’s a follower
   

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10. Tango & Control
    Inputs (follower)
    • Torso orientation
    • Distance between chests
    • Centre of gravity
    • Pressure on the back
    • Distance to other dancers
    • …

    Outputs (follower)
    • Leg movement
    • Arm movement
    • Hip position
    • Centre of gravity
    Needs constant
    attention
    Refined with
    experience
    

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11. TANGO & Control
    There’s a leader → Device Client
    There’s a follower → Device Server
    additional information to send on the wire, TANGO version control etc. These details can and should be
    wrapped in TANGO Application Programmer Interface (API). The API is implemented as a library in C++
    and as a package in Java. The API is what makes TANGO clients easy to write. The API’s consists the
    following basic classes :
    • DeviceProxy which is a proxy to the real device
    • DeviceData to encapsulate data send/receive from/to device via commands
    • DeviceAttribute to encapsulate data send/receive from/to device via attributes
    • Group which is a proxy to a group of devices
    In addition to these main classes, many other classes allows a full interface to TANGO features. The
    following figure is a drawing of a typical client/server application using TANGO.
    Client
    Database
    TANGO
    TANGO
    Server
    TANGO
    Cmd Attrib
    CORBA
    attrib
    CORBA
    opera
    API
    API
    Devices
    CORBA
    CORBA
    CORBA
    

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12. OK for one couple
    

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13. What about ballrooms?
    Control Strategy: Startup, Dance, Stop
    Distributed,
    autonomous
    control
    

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14. What about systems?
    Leaders are many times followers of other leaders
    (military hierarchy)
    Anyone could be a follower of anyone (swarms)
    Strategy allows for clear decision and action at the
    different levels
    Think
    hierarchically
    

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16. These are
    modes!
    (of the dancers)
    

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17. Or are they
    attributes?
    

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18. A TANGO Device Server
    Device server
    Instance Name
    State
    Attribute_1
    Attribute_2
    Attribute_3
    Attribute_4
    Command_1
    Command_2
    Command_3
    `
    ΅
    ῰
    Class-dependent
    Think
    hierarchically
    

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19. A TANGO Device Server
    Device server
    Instance Name
    State
    Attribute_1
    Attribute_2
    Attribute_3
    Attribute_4
    Command_1
    Command_2
    Command_3
    Think inheritance
    `
    ΅
    ῰
    Class-dependent
    

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20. A TANGO Hierarchy
    Device1 Device2 Device3 Device4
    

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21. A TANGO Hierarchy
    Device
    Server1
    Device
    Server2
    Device1 Device2 Device3 Device4
    

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22. A TANGO Hierarchy
    TEL-
    MGT
    Device
    Server1
    Device
    Server2
    Device1 Device2 Device3 Device4
    

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23. A TANGO Hierarchy
    TEL-
    MGT
    Device
    Server1
    Device
    Server2
    Device1 Device2 Device3 Device4
    DB
    

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24. A TANGO Hierarchy
    TEL-
    MGT
    Client1
    Client2
    Client3
    Device
    Server1
    Device
    Server2
    Device1 Device2 Device3 Device4
    DB
    

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25. A TANGO Hierarchy
    Client1 Client2
    Client3
    Device
    Server1
    Device
    Server2
    Device1 Device2 Device3 Device4
    DB
    

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26. A TANGO Hierarchy
    Device
    Server1
    Device
    Server2
    Device1 Device2 Device3 Device4
    DB
    Generic
    Client
    This is the
    power of TANGO
    

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27. A TANGO Hierarchy
    Device
    Server1
    Device
    Server2
    Device1 Device2 Device3 Device4
    DB
    Generic
    Client
    

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28. A TANGO Hierarchy
    Device
    Server1
    Device
    Server2
    Device1 Device2 Device3 Device4
    DB
    Generic
    Client
    

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29. A TANGO Hierarchy
    Device
    Server1
    Device
    Server2
    Device1 Device2 Device3 Device4
    DB
    Generic
    Client
    Generic
    Client
    Each one
    for each
    specialist
    

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30. A TANGO Hierarchy
    TEL-
    MGT
    Device
    Server1
    Device
    Server2
    Device1 Device2 Device3 Device4
    DB
    

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31. A TANGO Hierarchy
    Proxy1
    Device
    Server1
    Device
    Server2
    Device1 Device2 Device3 Device4
    DB
    Proxy2
    Device
    Server4
    Device
    Server3
    Device5 Device6 Device7 Device8
    TEL-
    MGT
    

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32. A TANGO Hierarchy
    Proxy1
    Device
    Server1
    Device
    Server2
    Device1 Device2 Device3 Device4
    DB
    Proxy2
    Device
    Server4
    Device
    Server3
    Device5 Device6 Device7 Device8
    TEL-
    MGT
    DB
    

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33. A TANGO Hierarchy
    Proxy1
    Device
    Server1
    Device
    Server2
    Device1 Device2 Device3 Device4
    DB
    Proxy2
    Device
    Server4
    Device
    Server3
    Device5 Device6 Device7 Device8
    TEL-
    MGT
    DB
    DB
    

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34. A TANGO Hierarchy
    Proxy1
    Device
    Server1
    Device
    Server2
    Device1 Device2 Device3 Device4
    DB
    Proxy2
    Device
    Server4
    Device
    Server3
    Device5 Device6 Device7 Device8
    TEL-
    MGT
    DB
    DB Can be
    scaled
    easily
    

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35. A TANGO Hierarchy
    Proxy1
    Device
    Server1
    Device
    Server2
    Device1 Device2 Device3 Device4
    DB
    Proxy2
    Device
    Server4
    Device
    Server3
    Device5 Device6 Device7 Device8
    TEL-
    MGT
    DB
    DB Allows for
    bottom-up
    building
    

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36. Not talking about…
    Commonality of attributes (LMC harmonisation)
    Having similar interfaces for similar devices
    (inheritance, device libraries, software harmonisation)
    Archiving and logging
    Time-stamping
    Synchronous vs. asynchronous
    And many others,
    included in TANGO
    

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37. How much control do you need
    to dance TANGO?
    Ability to keep track of own status (state, attributes),
    and perform “moves” (commands)
    Ability to measure attributes in others (read attributes)
    Signal others what is going to happen (write
    attributes), ask directly (command)
    Let others define the higher-level of control
    TANGO rules are embedded throughout
    

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38. Thank you!
    

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39. Questions?
    

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40. TANGO & SKA
    

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