DAQmxReadDigitalLines
int32 DAQmxReadDigitalLines (TaskHandle taskHandle, int32 numSampsPerChan, float64 timeout, bool32 fillMode, uInt8 readArray[], uInt32 arraySizeInBytes, int32 *sampsPerChanRead, int32 *numBytesPerSamp, bool32 *reserved);
Purpose
Reads multiple samples from each digital line in a task. Each line in a channel gets one byte per sample.
Parameters
| Input | |||||||||||
| Name | Type | Description | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| taskHandle | TaskHandle | The task to read samples from. | |||||||||
| numSampsPerChan | int32 | The number of samples, per channel, to read. The default value of -1 (DAQmx_Val_Auto) reads all available samples. If readArray does not contain enough space, this function returns as many samples as fit in readArray. NI-DAQmx determines how many samples to read based on whether the task acquires samples continuously or acquires a finite number of samples. If the task acquires samples continuously and you set this parameter to -1, this function reads all the samples currently available in the buffer. If the task acquires a finite number of samples and you set this parameter to -1, the function waits for the task to acquire all requested samples, then reads those samples. If you set the Read All Available Data property to TRUE, the function reads the samples currently available in the buffer and does not wait for the task to acquire all requested samples. |
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| timeout | float64 | The amount of time, in seconds, to wait for the function to read the sample(s). The default value is 10.0 seconds. To specify an infinite wait, pass -1 (DAQmx_Val_WaitInfinitely). This function returns an error if the timeout elapses. A value of 0 indicates to try once to read the requested samples. If all the requested samples are read, the function is successful. Otherwise, the function returns a timeout error and returns the samples that were actually read. |
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| fillMode | bool32 | Specifies whether or not the samples are interleaved.
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| arraySizeInBytes | uInt32 | The size of the array, in samples, into which samples are read. | |||||||||
| reserved |
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Reserved for future use. Pass NULL to this parameter. | |||||||||
| Output | |||||||||||
| Name | Type | Description | |||||||||
| readArray |
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The array to read samples into. Each numBytesPerSamp corresponds to one sample per channel, with each element in that grouping corresponding to a line in that channel, up to the number of lines contained in the channel. | |||||||||
| sampsPerChanRead |
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The actual number of samples read from each channel. | |||||||||
| numBytesPerSamp |
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The number of elements in readArray that constitutes a sample per channel. For each sample per channel, numBytesPerSamp is the number of bytes that channel consists of. |
Return Value
| Name | Type | Description |
|---|---|---|
| status | int32 | The error code returned by the function in the event of an error or warning. A value of 0 indicates success. A positive value indicates a warning. A negative value indicates an error. |