viDiscardEvents
Syntax
viDiscardEvents(ViSession vi, ViEventType eventType, ViUInt16 mechanism);
Description
This function discards all pending occurrences of the specified event types for the mechanisms specified in a given session. The information about all the event occurrences that have not yet been handled is discarded. This function is useful to remove event occurrences that an application no longer needs.
The event occurrences discarded by applications are not available to a session at a later time. This operation causes loss of event occurrences. The viDiscardEvents operation does not apply to event contexts that have already been delivered to the application.
Parameters
|
Name |
Dir |
Type |
Description |
|
vi |
IN |
ViSession |
Unique logical identifier to a session. |
|
eventType |
IN |
ViEventType |
Logical event identifier. (See the following tables.) |
|
mechanism |
IN |
ViUInt16 |
Specifies the mechanisms for which the events are to be discarded. VI_QUEUE is specified for the queuing mechanism and VI_SUSPEND_HNDLR is specified for the pending events in the callback mechanism. It is possible to specify both mechanisms simultaneously by specifying VI_ALL_MECH. |
|
Special Values for eventType Parameter |
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Value |
|
|
Action Description |
|
VI_ALL_ENABLED_EVENTS |
|
|
Discard events of every type that is enabled. |
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The following events can be discarded: |
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Event Name |
|
|
Description |
|
VI_EVENT_IO_COMPLETION |
|
|
Notification that an asynchronous operation has completed. |
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VI_EVENT_TRIG |
|
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Notification that a hardware trigger was received from a device. |
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VI_EVENT_SERVICE_REQ |
|
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Notification that a device is requesting service. |
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VI_EVENT_CLEAR |
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Notification that the local controller has been sent a device clear message |
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VI_EVENT_EXCEPTION |
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Notification that an error condition has occurred during an operation invocation. (Note: the VI_QUEUE and VI_SUSPEND_HNDLR mechanisms cannot be used with this event.) |
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VI_EVENT_GPIB_CIC |
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Notification that the GPIB controller has gained or lost CIC (controller in charge) status. |
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VI_EVENT_GPIB_TALK |
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Notification that the GPIB controller has been addressed to talk. |
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VI_EVENT_GPIB_LISTEN |
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Notification that the GPIB controller has been addressed to listen. |
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VI_EVENT_PXI_INTR |
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Notification that a vendor-specific PXI interrupt was received from the device. |
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VI_EVENT_VXI_VME_SYSFAIL |
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Notification that the VXI/VME SYSFAIL* line has been asserted. |
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VI_EVENT_VXI_VME_SYSRESET |
|
|
Notification that the VXI/VME SYSRESET* line has been asserted |
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VI_EVENT_VXI_SIGP |
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|
Notification that a VXI signal or VXI interrupt has been received from a device. |
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VI_EVENT_VXI_VME_INTR |
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Notification that a VXIbus interrupt was received from the device. |
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Not supported by Agilent VISA: |
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VI_EVENT_TCPIP_CONNECT |
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Notification that a TCP/IP connection has been made. |
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VI_EVENT_USB_INTR
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Notification that a vendor-specific USB interrupt was received from the device. |
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Note: Refer to the viEventHandler topic and the VISA Attributes topics for information on the event types that are available for various VISA resource classes (e.g. INSTR, INTFC …). |
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Special Values for mechanism Parameter |
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|
Value |
|
|
Action Description |
|
VI_ALL_MECH |
|
|
Discard the specified event(s) from all mechanisms. |
|
VI_QUEUE |
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|
Discard the specified event(s) from the waiting queue. |
|
VI_SUSPEND_HNDLR |
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|
Discard the specified event(s) from the callback queue. |
Return Values
|
Type ViStatus |
This is the function return status. It returns either a completion code or an error code as follows. |
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Completion Codes |
Description |
|
VI_SUCCESS |
Event queue flushed successfully. |
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VI_SUCCESS_QUEUE_EMPTY |
Operation completed successfully, but queue was empty. |
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Error Codes |
Description |
|
VI_ERROR_INV_EVENT |
Specified event type is not supported by the resource. |
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VI_ERROR_INV_MECH |
Invalid mechanism specified. |
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VI_ERROR_INV_SESSION |
The given session or object reference is invalid (both are the same value). |
See Also
viEnableEvent, viWaitOnEvent, viInstallHandler