Instrument Control Toolbox

Event Types and Callback Properties

The GPIB event types and associated callback properties are described below.

Table 3-9: GPIB Event Types and Callback Properties  

Event Type	Associated Property Name
Bytes available	BytesAvailableFcn
	BytesAvailableFcnCount
	BytesAvailableFcnMode
Error	ErrorFcn
Output empty	OutputEmptyFcn
Timer	TimerFcn
	TimerPeriod

Bytes-Available Event.   A bytes-available event is generated immediately after a predetermined number of bytes are available in the input buffer or the End-Of-String character is read, as determined by the BytesAvailableFcnMode property.

If BytesAvailableFcnMode is byte, the bytes-available event executes the callback function specified for the BytesAvailableFcn property every time the number of bytes specified by BytesAvailableFcnCount is stored in the input buffer. If BytesAvailableFcnMode is eosCharCode, then the callback function executes every time the character specified by the EOSCharCode property is read.

This event can be generated only during an asynchronous read operation.

Error Event.   An error event is generated immediately after an error, such as a timeout, occurs. A timeout occurs if a read or write operation does not successfully complete within the time specified by the Timeout property. An error event is not generated for configuration errors such as setting an invalid property value.

This event executes the callback function specified for the ErrorFcn property. It can be generated only during an asynchronous read or write operation.

Output-Empty Event.   An output-empty event is generated immediately after the output buffer is empty.

This event executes the callback function specified for the OutputEmptyFcn property. It can be generated only during an asynchronous write operation.

Timer Event.   A timer event is generated when the time specified by the TimerPeriod property passes. Time is measured relative to when the object is connected to the instrument.

This event executes the callback function specified for the TimerFcn property. Note that some timer events might not be processed if your system is significantly slowed or if the TimerPeriod value is too small.

Events and Callbacks

Storing Event Information