NI PXI-5404
Locking to a Reference Clock

The onboard clock of the NI PXI-5404 can be locked to an external reference signal. This can be used when synchronizing multiple NI 5404 signal generators or whenever the output frequency needs to be locked to some external source. If no reference source is specified, the device will use an internal reference that can be adjusted during a device calibration.

The Reference clock source can be configured using the niFgen Configure Reference Clock VI or the niFgen_ConfigureReferenceClock function or by setting the Reference Clock Source property or NIFGEN_ATTR_REF_CLOCK_SOURCE attribute directly. In addition to specifying the source of the Reference clock signal, you must also specify its frequency. The Reference clock frequency can be configured using the niFgen Configure Reference Clock VI or the niFgen_ConfigureReferenceClock function or by setting the Reference Clock Frequency property or the NIFGEN_ATTR_REF_CLOCK_FREQUENCY attribute directly. The NI PXI-5404 can lock to 3 MHz to 20 MHz frequencies (in 1 MHz steps).

Reference Source	Description
NIFGEN_VAL_REF_CLOCK_INTERNAL	No external reference is used. The device uses an internal reference.
NIFGEN_VAL_PXI_CLK10	10 MHz PXI backplane clock.
NIFGEN_VAL_REF_IN	REF IN connector on the NI 5404 front panel.
NIFGEN_VAL_RTSI_<0..6>	One of the RTSI/PXI trigger lines
NIFGEN_VAL_REF_CLOCK_RTSI_CLOCK	RTSI clock line (RTSI_7/PXI_Trig7)

The following table lists the NI-FGEN synchronization examples for various ADEs.

ADE	Path
LabVIEW	<LabVIEW>\examples\instr\niFgen\niFgen_5404_Synchronization_Example.vi
LabWindows/CVI	<CVI>\Samples\niFgen\Synchronization5404.prj
C++	<MeasurementStudio>\VC\Examples\niFgen\niFgen_5404_Synchronization_Ex\niFgen_5404_Synchronization_Example.dsw
Visual Basic	<MeasurementStudio>\VB\Samples\niFgen\5404_Synchronization_Example.vbp
Standard C	<Program Files>\IVI\Drivers\niFgen\Examples\c\Synchronization5404.c