How to Make a Private MDSplus Tree

(the steps shown here are for VMS; similar things can be done on Linux. If you wish to start with an existing tree, see <"http://nstx.pppl.gov/nstx/Software/images/redbar.gif"> the Location of files making up an MDSplus tree)

pick a nice name: yourname
(for access from a remote Unix node, this is by convention your VAX username)

create the logical name yourname$DATA

    EUROPA$ define yourname$data yourname$:[mds.testdata]

(the directory can be anything you have write access to )

create a "model tree" in the yourname$DATA directory:
```
   
    An easy way is to copy an empty template:

    EUROPA$ copy autil:[mdsplus.emptytree]emptytree_model.*  -
           yourname$data:yourname_model.*
 
```
NOTE: If you want to access this test tree from Unix, this logical name must be a SYSTEM logical name on EUROPA. Send email to nstx_sw_dev@pppl.gov if you need to access your private MDSplus tree from UNIX.

To find an existing model tree from which to start, see How to find the files of an MDSplus Tree

Create nodes in your new tree using the TRAVERSER app (or TCL commands)

    
    EUROPA$ setup mdsplus

    EUROPA$ traverser -tree yourname -shot -1 -edit

    (shot -1 is the model tree)
    
    In Traverser, select "TOP" with the mouse, 
    then select Edit...Add Node...Signal. 
    
    Enter a Node Name, say onedim. 
    
    Quit Traverser while saving the tree.

Copy the model tree to another shot number, say to 10:
Note that the "shot" number is actually just an ID number and need not be related to an actual shot. In fact, ID numbers for TRANSP runs are NOT shot numbers (there is a database that relates shots and ID numbers).
```
    
    EUROPA$ tcl
    TCL> set tree yourname
    TCL> create pulse 10
    TCL> exit
 
```

Write to your signal

    
    EUROPA$ idl
    IDL> MDSOPEN, 'yourname', 10
    IDL> x = FINDGEN(10)  &  data = x ^2
    IDL> mdsput,':onedim','build_signal($,*,$)',data, x

Read it back

    
    EUROPA$ idl
    IDL> MDSOPEN, 'yourname', 10
    IDL> print, MDSVALUE(':onedim')

You may also examine the signal's contents in Traverser.

for help with TCL see http://snax.pppl.gov/~roney/nstx

Go (back) to the MDS Access Examples

Comments can be mailed to bdavis.

How to Make a Private MDSplus Tree

updated: 27-Mar-2007 by: Bill Davis

updated: 27-Mar-2007
by: Bill Davis