Configuring and Returning Properties
Configuring Property Names and Property Values
You establish the desired instrument object behavior by configuring
property values. You can configure property values using the
set function or the dot notation,
or by specifying property name/property value pairs during object
creation. You can return property values using the
get function or the dot notation.
Interface objects possess two types of properties: base
properties and interface-specific properties.
(These properties pertain only to the interface object itself and
to the interface, not to the instrument.) Base
properties are supported for all interface objects (serial port, GPIB,
VISA-VXI, and so on), while interface-specific properties are supported
only for objects of a given interface type. For example, the
is supported only for serial port and VISA-serial objects.
Device objects also possess two types of properties: base
properties and device-specific properties.
While device objects possess base properties pertaining to the object
and interface, they also possess any number of device-specific properties
as defined in the instrument driver for configuring the instrument.
For example, a device object representing an oscilloscope might posses
such properties as
MeasurementMode. When you set these properties
you are directly configuring the oscilloscope settings.
Returning Property Names and Property Values
Once the instrument object is created, you can use the
set function to return all its configurable
properties to a variable or to the command line. Additionally, if
a property has a finite set of character vector values,
Using Tab Completion for Functions
To get a list of options you can use on the function, press the
Tab key after entering a function on the MATLAB® command line. The list expands, and you can scroll to choose a
property or value. For example, when you create a
you can get a list of installed vendors:
g = gpib('
When you press Tab after the parentheses and single quote,
as shown here, the list of installed GPIB vendors displays, such as
The format for the GPIB object constructor function is:
g = gpib('vendor',boardindex,primaryaddress)
When you press Tab where a field should appear, you get the list of options for that field. The other interface objects, such as Bluetooth®, Serial, TCP/IP, etc., also include this capability on their object constructor functions.
You can also get the values for property-value pairs. For example, to get the possible terminator values when creating a serial object, type:
s = serial('COM1','Terminator','
Press Tab after typing the single quote after
Terminator to get the possible values for that property, as
Many of the other toolbox functions also have tab completion. For example, when
fread function you can specify the precision type using
data = fread(s,256,'
Press Tab after typing the single quote after the
size (256 values in this example), since precision is the
next argument the
fread function takes, to get the possible
values for the precision types, such as
When the list of possible values is long, a scroll bar appears in the pop-up window, as shown in this example.
The Property Inspector enables you to inspect and set properties for one or more instrument objects. It provides a list of all properties and displays their current values.
Settable properties in the list are associated with an editing
device that is appropriate for the values accepted by the particular
property. For example, a callback configuration GUI to set
a pop-up menu to set
RecordMode, and a text field
to specify the
TimerPeriod. The values for read-only
properties are grayed out.
You open the Property Inspector with the
inspect function. Alternatively, you
can open the Property Inspector via the Workspace browser by right-clicking
an instrument object and selecting Call Property
Inspector from the context menu, or by double-clicking