NI-TClk
Performance Optimization

To ensure correct synchronization, you must call the niTClk Synchronize VI or the niTClk_Synchronize function every time you change a clocking or sample rate attribute for a TClk-synchronized device. Each call to the niTClk Synchronize VI or the niTClk_Synchronize function adds time to the application execution.

To optimize the performance of your application, set the clocking and sample rate attributes only once, then call the niTClk Synchronize VI or the niTClk_Synchronize function.

You do not need to call the niTClk Synchronize VI or the niTClk_Synchronize function every time you initiate or start an acquisition unless you are changing attributes that affect clocking or sample rate. These attributes are listed in the table below. For the NI 5922 digitizer, this list of attributes also includes channel-based attributes.

Caution  NI-TClk does not detect any changes to the relevant attributes. Therefore, no errors are reported if the devices become unsynchronized because of an attribute change. You must remember to resynchronize if any of these attributes change.

Note   You should call the niTClk Configure for Homogenous Trigers VI the niTClk_ConfigureForHomogeneousTriggers function any time any driver attribute changes value.

Driver	LabVIEW Property	C Attribute	Comment
NI-FGEN	Sample Rate	NIFGEN_ATTR_ARB_SAMPLE_RATE
NI-FGEN	Update Clock Source	NIFGEN_ATTR_UPDATE_CLOCK_SOURCE
NI-FGEN	Clock Mode	NIFGEN_ATTR_CLOCK_MODE
NI-FGEN	Reference Clock Source	NIFGEN_ATTR_REF_CLOCK_SOURCE
NI-FGEN	Reference Clock Frequency	NIFGEN_ATTR_REF_CLOCK_FREQUENCY
NI-FGEN	Frequency	NIFGEN_ATTR_FUNC_FREQUENCY	Only applies to some devices
NI-FGEN	Waveform	NIFGEN_ATTR_FUNC_WAVEFORM	Only applies to some devices
NI-FGEN	OSP Enabled	NIFGEN_ATTR_OSP_ENABLED
NI-FGEN	IQ Rate	NIFGEN_ATTR_OSP_IQ_RATE
NI-FGEN	CIC Interpolation Factor	NIFGEN_ATTR_OSP_CIC_FILTER_INTERPOLATION
NI-FGEN	FIR Interpolation Factor	NIFGEN_ATTR_OSP_FIR_FILTER_INTERPOLATION
NI-HSDIO	RefClk.Source	NIHSDIO_ATTR_REF_CLOCK_SOURCE
NI-HSDIO	RefClk.Rate	NIHSDIO_ATTR_REF_CLOCK_RATE
NI-HSDIO	RefClk.Impedance	NIHSDIO_ATTR_REF_CLOCK_IMPEDANCE	Only with external reference clock
NI-HSDIO	SampClk.Source	NIHSDIO_ATTR_SAMPLE_CLOCK_SOURCE
NI-HSDIO	SampClk.Rate	NIHSDIO_ATTR_SAMPLE_CLOCK_RATE
NI-HSDIO	SampClk.Impedance	NIHSDIO_ATTR_SAMPLE_CLOCK_IMPEDANCE	Only with external sample clock
NI-SCOPE	Min Sample Rate	NISCOPE_ATTR_MIN_SAMPLE_RATE
NI-SCOPE	Input Clock Source	NISCOPE_ATTR_CLOCK_SOURCE
NI-SCOPE	Reference Clock Rate	NISCOPE_ATTR_REF_CLK_RATE
NI-SCOPE	Sample Clock Timebase Source	NISCOPE_ATTR_SAMP_CLK_TIMEBASE_SRC
NI-SCOPE	Sample Clock Timebase Rate	NISCOPE_ATTR_SAMP_CLK_TIMEBASE_RATE
NI-SCOPE	Sample Clock Timebase Divsor	NISCOPE_ATTR_SAMP_CLK_TIMEBASE_DIV
NI-SCOPE	Max Input Frequency	NISCOPE_ATTR_MAX_INPUT_FREQUENCY	Only applies to some devices