AlazarAsyncRead Sample Clauses

AlazarAsyncRead. ‌ Some C/C++ applications under Windows may require waiting for an event to be set to the signaled state to indicate when an AutoDMA buffer is full. These applications should use the AlazarAsyncRead API. The following code fragment outlines how use AlazarAsyncRead to make an asynchronous AutoDMA acquisition. // Configure the board to make an AutoDMA acquisition AlazarBeforeAsyncRead( handle, // HANDLE -- board handle channelMask, // U32 -- enabled channel mask -(long)preTriggerSamples, // long -- trigger ofset samplesPerBuffer, // U32 -- samples per buffer recordsPerBuffer, // U32 -- records per buffer recordsPerAcquisition, // U32 -- records per acquisition admaFlags // U32 -- AutoDMA flags ); // Add two or more buffers to a list of buffers // available to be filled by the board for (i = 0; i < BUFFER_COUNT; i++) { AlazarAsyncRead ( handle, // HANDLE -- board handle IoBufferArray[i].buffer, // void* -- buffer IoBufferArray[i].bytesPerBuffer, // U32 -- buffer length &IoBufferArray[i].overlapped // OVERLAPPED* ); } // Arm the board to begin the acquisition AlazarStartCapture(handle); // Wait for each buffer in the acquisition to be filled. U32 buffersCompleted = 0; while (buffersCompleted < buffersPerAcquisition) { // Wait for the board to receives sufficient // trigger events to fill the buffer at the head of its // list of available buffers. // The event handle will be set to the signaled state when // the buffer is full. U32 bufferIndex = buffersCompleted % BUFFER_COUNT; IO_BUFFER *pIoBuffer = IoBufferArray[bufferIndex]; WaitForSingleObject(pIoBuffer->hEvent, INFINTE); buffersCompleted++; // The buffer is full, process it // Note that while the application processes this buffer, // the board is filling the next available buffer // as trigger events arrive. ProcessBuffer(pIoBuffer->buffer, pIoBuffer->bytesPerBuffer); // Add the buffer to the end of the list of buffers. // The board will fill it with another segment from the // acquisition after the buffers preceding it have been filled. AlazarAsyncRead ( handle, // HANDLE -- board handle pIoBuffer->buffer, // void* -- buffer pIoBuffer->bytesPerBuffer, // U32 -- buffer length &pIoBuffer->overlapped // OVERLAPPED* ); } // Stop the acquisition. // This function must be called if unfilled buffers are pending. AlazarAbortAsyncRead(handle); See “%ATS_SDK_DIR%\Samples\DualPort\CS_AsyncRead” for a full sample program that demonstrates make an AutoDMA acquisition using AlazarAsyncRead.

AlazarAsyncRead. ‌ Add a buffer to the end of a list of buffers available to be filled by the board. When the board receives sufficient trigger events to fill the buffer, the event in the OVERLAPPED will be set to the signaled state. Syntax C/C++ RETURN_CODE AlazarAsyncRead( HANDLE BoardHandle, void *Buffer, U32 BytesToRead, OVERLAPPED *Overlapped ); VisualBasic Not available Parameters BoardHandle [in] Handle to board. Buffer [out] Pointer to a buffer to receive sample data from the digitizer board. BytesToRead [in] Specifies the number of bytes to read from the board. BytesToRead [in] Pointer to an OVERLAPPED structure. The event in the OVERLAPPED structure is set to the signaled state when the read operation completes. Return value If the function succeeds in adding the buffer to end of the list of buffers available to be filled by the board, it returns ApiDmaPending (585). When the board fills the buffer, the event in the OVERLAPPED structure is to the signaled state. If the function fails because the board overflowed its on-board memory, it returns ApiBufferOverflow (582). The board may overflow its on-board memory because the rate at which it is acquiring data is faster than the rate at which it is transferring data from on-board memory to host memory. If this is the case, try reducing the sample rate, number of enabled channels, or amount of time spent processing each buffer. If the function fails because the buffer is too large for the driver or operating system to prepare for scatter-gather DMA transfer, it returns ApiLockAndProbePagesFailed (586). Try reducing the size of each buffer, or reducing the number of buffers queued by the application. If the function fails for some other reason, it returns an error code that indicates the reason that it failed. See Table 1 for a list of error codes. Remarks AlazarAsyncRead is only available under Windows. You must call AlazarBeforeAsyncRead before calling AlazarAsyncRead. You must call AlazarAbortAsyncRead before your application exits if you have called AlazarAsyncRead, and buffers are pending when you wish to exit your application. The BytesToRead parameter must be equal to the product of the number of bytes per record, the number of records per buffer, and the number of enabled channels. If record headers are enabled, the number of bytes per record must include the size of the record header (16 bytes). See Also AlazarAbortAsyncRead AlazarBeforeAsyncRead Using asynchronous AutoDMA