Instrument Control Toolbox

Saving and Loading Instrument Objects

You can save an instrument object to disk using two possible formats:

• As an M-file using the obj2mfile function
• As a MAT-file using the save command

You can also save data transferred between the object and the instrument using these two functions. However, it is easier to use the record function for this purpose as described in Debugging: Recording Information to Disk.

Saving Instrument Objects to an M-File

You can save an instrument object to an M-file using the obj2mfile function. obj2mfile provides you with these options:

• Save all property values or save only those property values that differ from their default values.

• Read-only property values are not saved. Therefore, read-only properties use their default values when you load the instrument object into the MATLAB workspace. To determine if a property is read-only, use the propinfo function or examine the property reference pages.

• Save property values using the set syntax or the dot notation.

• If the UserData property is not empty, or if a callback property is set to a cell array of values or a function handle, then the data stored in these properties is written to a MAT-file when the instrument object is saved. The MAT-file has the same name as the M-file containing the instrument object code.

For example, suppose you create the GPIB object g, return instrument identification information to the variable out, and store out in the UserData property.

• g = gpib('ni',0,1);
  g.Tag = 'My GPIB object';
  fopen(g)
  cmd = '*IDN?';
  fprintf(g,cmd)
  out = fscanf(g);
  g.UserData = out;
  

The following command saves g and the modified property values to the M-file mygpib.m. Because the UserData property is not empty, its value is automatically written to the MAT-file mygpib.mat.

• obj2mfile(g,'mygpib.m');
  

Use the type command to display mygpib.m at the command line.

Loading the Instrument Object

To load an instrument object that was saved as an M-file into the MATLAB workspace, type the name of the M-file at the command line. For example, to load g from the M-file mygpib.m:

• g = mygpib
  

The display summary for g is shown below. Note that the read-only properties such as Status, BytesAvailable, ValuesReceived, and ValuesSent are restored to their default values.

• GPIB Object Using NI Adaptor : GPIB0-1
  
  Communication Address 
     BoardIndex:         0
     PrimaryAddress:     1
     SecondaryAddress:   0
  
  Communication State 
     Status:             closed
     RecordStatus:       off
  
  Read/Write State  
     TransferStatus:     idle
     BytesAvailable:     0
     ValuesReceived:     0
     ValuesSent:         0
  

When loading g into the workspace, the MAT-file mygpib.mat is automatically loaded and the UserData property value is restored.

• g.UserData
  ans =
  TEKTRONIX,TDS 210,0,CF:91.1CT FV:v1.16 TDS2CM:CMV:v1.04
  

Saving and Loading the Session

Saving Objects to a MAT-File