Interchangeability Checking
Interchangeability warnings indicate that using your application with a different instrument might cause different behavior. Use the ClassPrefix Get Next Interchange Warning VI to retrieve interchangeability warnings. Alternately, you may use NI Spy to view interchangeability warnings.
Interchangeability checking is performed on a capability group basis. When enabled, interchangeability checking is always performed on the base capability group. Interchangeability checking is performed on extension capability groups when you have set a value for any property in the group. If you never set the value of any property of an extension capability group, interchangeability checking is not performed on that group.
In general, interchangeability warnings are generated if the following conditions are encountered:
- A property that affects the behavior of the instrument is not in a state that you specify. This can happen if your program does not configure the property or if your program configures the property but the value becomes invalid as a result of your program configuring a different property.
- You set or get an instrument specific property.
- You set an property for which the IVI class specification defines values to an instrument specific value.
- You pass an instrument specific value to a VI parameter for which the IVI class specification defines values.
- You attempt to set an property that the class defines as read-only. In some cases the class drivers define read-only properties that specific drivers might implement as read/write.
- The class driver encounters an error when it tries to disable an extension capability group that your program does not use. The purpose of disabling unused extension groups is to make your program behave the same regardless of whether the instruments you use implement the extension capability group. Some instruments that implement the extension capability group might not support the value to which the class driver attempts to set the property. In this case, the class driver queues an interchangeability warning instead of returning an error from the VI.
Related Topics
ClassPrefix Clear Interchange Warnings
ClassPrefix Get Next Interchange Warning
ClassPrefix Reset Interchange Check
Click the following links to learn more about interchangeability checking for a particular IVI class driver.