Type: SystemInt32 The number of samples to read. If you set numberOfSamples to -1 for a continuous acquisition, the read retrieves all samples available in the buffer at the time of the read. If you set numberOfSamples to -1 for a finite acquisition, the read behavior is set by the ReadAllAvailableSamples property of the DaqStream you are reading from.
data
Type: NationalInstruments.DAQmxCIDataTime An initialized 1D array of CIDataTime samples that contains the read data. Each element in the array corresponds to a sample from the channel.
actualNumberOfSamplesRead
Type: SystemInt32 The actual number of samples read. This is useful when the reading operation yields fewer or more samples than the actual length of data.
Return Value
Type: CIDataTime A reference to the data parameter containing samples from the task.
If the first dimension of data does not match the number of channels; or
If ReallocationPolicy is not ToGrow, and data is not capable of holding the required number of samples.
OutOfMemoryException
There is not enough memory to carry out this operation.
Remarks
If the data buffer is large enough to hold the number of samples requested, this overload attempts to reuse existing memory allocated from the array to acquire data. This results in more efficient memory allocation when performing multiple reads with a continuous counter input task. The memory allocation for the buffer is available to a maximum of 2 GB.
NI-DAQmx scales the returned data to the units of the measurement, including any custom scaling you apply to the channel. You specify these units with the create channel methods or the
DAQ Assistant.
NI-DAQmx read and write methods time out after the amount of time specified by the
Timeout
property on the task you are reading from or writing to.