VISA Events

VISA defines a common mechanism to notify an application when certain conditions occur. These conditions or occurrences are referred to as events. An event is a means of communication between a VISA resource and its applications. Typically, events occur because of a condition requiring the attention of applications.

The VISA event model provides the following two different ways for an application to receive event notification:

The queuing and callback mechanisms are suitable for different programming styles. However, because these mechanisms work independently of each other, you can have them both enabled at the same time.

The following topics describe the VISA event model and how to use it. They discuss the various events VISA supports and the event handling paradigm.

Supported Events

Enabling and Disabling Events

Queuing

Callbacks

Callback Modes

Independent Queues

The userHandle Parameter

Queuing and Callback Mechanism Sample Code

The Life of the Event Context

Event Context with the Queuing Mechanism

Event Context with the Callback Mechanism

Exception Handling