Data Acquisition Toolbox

The propinfo Function

You can use the propinfo function to return the characteristics of Data Acquisition Toolbox properties. For example, you can find the default value for any property using this function. propinfo returns a structure containing the fields shown below.

Table 2-2: propinfo Fields  

Field Name	Description
Type	The property data type. Possible values are action function, any, double, and string.
Constraint	The type of constraint on the property value. Possible values are action function, bounded, enum, and none.
ConstraintValue	The property value constraint. The constraint can be a range of valid values or a list of valid string values.
DefaultValue	The property default value.
ReadOnly	If the property is read-only, a 1 is returned. Otherwise, a 0 is returned.
ReadOnlyRunning	If the property is read-only while the device object is running, a 1 is returned. Otherwise, a 0 is returned.
DeviceSpecific	If the property is device-specific, a 1 is returned. If a 0 is returned, the property is supported for all device objects of a given type.

For example, to return the characteristics for all the properties associated with the analog input object ai created in the preceding section

AIinfo = propinfo(ai);

The characteristics for the TriggerType property are displayed below.

AIinfo.TriggerType
ans = 
               Type: 'string'
         Constraint: 'Enum'
    ConstraintValue: {3x1 cell}
       DefaultValue: 'Immediate'
           ReadOnly: 0
    ReadOnlyRunning: 1
     DeviceSpecific: 0

This information tells you that:

• The property value data type is a string.
• The property value is constrained as an enumerated list of values.
• There are three possible property values.
• The default value is Immediate.
• The property is not read-only.
• You cannot configure the property while the device object is running.
• The property is supported for all analog input objects.

To display the property value constraints

AIinfo.TriggerType.ConstraintValue
ans = 
    'Manual'
    'Immediate'
    'Software'

The daqhelp Function

Using the Data Acquisition Toolbox