Reading MDSplus Data

JETDSP can read data through MDSplus. This can be used for JET data, and also for experimental data from other institutions stored in an MDSplus tree. It can also be used to read data from trees stored on your computer.

To read data via MDSplus, choose the Read Signal option from the File menu of the main window, and then the MDS+ tab at the top:

You must enter the name of the MDSplus server, the shot number and tree name in the relevant fields.

To read a specific signal enter the appropriate Signal name in the signal field, and press Read. There may be a slight delay when first reading a signal as the program connects to the MDSplus server. You can read in many different signals by entering the relevant signal name and then pressing Read. When you have read all the signals of interest, press Done.

JET data

JET data can be retrieved with the following parameters:

• MDS+ server: mdsplus.jet.efda.org
• Shot number: the JET pulse number you wish to read
• Tree: JPF for raw data, PPF for processed pulse file data

For these trees, the signal name is sepcified by dda and datatype for a PPF, or the subsystem and node name for a JPF. Each part of the signal name is delimited by a . so example PPF or JPF signals might be

• (PPF) magn.ipla
• (JPF) kk3.te20
• (JPF) da.c2-ipla

Browsing an MDSplus tree

The tree can be browsed to find signals of interest. To do this, enter the MDSPlus server name, tree name and shot number which you wish to browse. Then press the 'Browse Tree...' button. The below window will be displayed, which you can use to browse the MDSplus tree.

In this tree traverser window, the topmost text field shows the current location in the tree. Below this are two lists, the left-hand list indicates all structure nodes (ie branch nodes and sub-trees) from the current tree location. The right-hand list gives all signal type nodes at the current tree location. At present only signal type nodes are listed, and not any other data containing nodes. This is because all signals which can be plotted should be stored as Signal type. Other data-containing node types can be included in the listing, however, if this is requested.

To move to a different branch in the tree, click that branch in the left hand panel and the traverser details will be updated with the details from the new branch node. To return to the previous (parent) branch click the Up a level button. To return to the topmost branch, click the Return to \TOP button.

Use the traverser to find the name of the Signal of interest, select this by clicking on it in the Signals list, as above, and press OK. The selected Signal name should then be entered in the Signal field of the Read a Signal window. Press the Read button in this window to read the signal.