• NIRFSA_ATTR_REF_CLOCK_SOURCE
• NIRFSA_ATTR_REF_CLOCK_RATE
• NIRFSA_ATTR_EXPORTED_REF_CLOCK_OUTPUT_TERMINAL
• NIRFSA_ATTR_DIGITIZER_SAMPLE_CLOCK_RATE
• NIRFSA_ATTR_DIGITIZER_SAMPLE_CLOCK_TIMEBASE_SOURCE
• NIRFSA_ATTR_DIGITIZER_SAMPLE_CLOCK_TIMEBASE_RATE
• NIRFSA_ATTR_PXI_CHASSIS_CLK10_SOURCE
• NIRFSA_ATTR_EXPORTED_DIGITIZER_SAMPLE_CLOCK_OUTPUT_TERMINAL

Data type	Access	High Level Functions
ViString	R/W	niRFSA_ConfigureRefClock

Specifies the Reference Clock source.

	Note  For the PXIe-5694, if your application requires an external LO source, set this attribute to NIRFSA_VAL_NONE_STR.
Defined Values:

NIRFSA_VAL_NONE_STR ("None")	No Reference Clock is required for the current device configuration. This value is valid only for the PXIe-5694 or the PXIe-5668.
NIRFSA_VAL_ONBOARD_CLOCK_STR ("OnboardClock")	**PXI-5661—**NI-RFSA locks the NI-RFSA device to the PXI-5600 RF downconverter onboard clock. **PXIe-5663/5663E—**NI-RFSA locks the PXIe-5663/5663E to the PXI/PXIe-5652 LO source onboard clock. Connect the REF OUT2 connector (if it exists) on the PXI/PXIe-5652 to the CLK IN terminal on the PXIe-5622. On versions of the PXIe-5663/5663E that lack a REF OUT2 connector on the PXI/PXIe-5652, connect the REF IN/OUT connector on the PXI/PXIe-5652 to the CLK IN terminal on the PXI5622. **PXIe-5665—**NI-RFSA locks the PXIe-5665 to the PXIe-5653 LO source onboard clock. Connect the 100 MHz REF OUT terminal on the PXIe-5653 to the CLK IN terminal on the PXIe-5622. **PXIe-5667—**NI-RFSA locks the PXIe-5667 to the PXIe-5653 LO source onboard clock. Connect the 100 MHz REF OUT terminal on the PXIe-5653 to the CLK IN terminal on the PXIe-5622, and connect the 10 MHZ REF OUT terminal on the PXIe-5653 to the REF/LO IN connector on the PXIe-5694. **PXIe-5668—**Lock the PXIe-5668 to the PXIe-5653 LO SOURCE onboard clock. Connect the LO2 OUT connector on the PXIe-5606 to the CLK IN connector on the PXIe-5624. **PXIe-5830/5831—**For the PXIe-5830, connect the PXIe-5820 REF IN connector to the PXIe-3621 REF OUT connector. For the PXIe-5831/5832, connect the PXIe-5820 REF IN connector to the PXIe-3622 REF OUT connector. **PXIe-5831/5832 with PXIe-5653—**Connect the PXIe-5820 REF IN connector to the PXIe-3622 REF OUT connector. Connect the PXIe-5653 REF OUT (10 MHz) connector to the PXIe-3622 REF IN connector. **PXIe-5644/5645/5646, PXIe-5820/5840/5841—**Lock the NI-RFSA device to its onboard clock. **PXIe-5841 with PXIe-5655—**Lock to the PXIe-5655 onboard clock. Connect the REF OUT connector on the PXIe-5655 to the PXIe-5841 REF IN connector.
NIRFSA_VAL_REF_IN_STR ("RefIn")	**PXI-5661—**NI-RFSA locks the NI-RFSA device to the signal at the external FREQ REF IN connector on the PXI-5600. **PXIe-5663/5663E—**Connect the external signal to the PXI/PXIe-5652 REF IN/OUT connector. Connect the REF OUT2 connector (if it exists) on the PXI/PXIe-5652 to the CLK IN terminal on the PXIe-5622. On versions of the PXIe-5663/5663E that lack a REF OUT2 connector on the PXI/PXIe-5652, this configuration can only be used in external digitizer mode. **PXIe-5665—**Connect the external signal to the PXIe-5653 REF IN connector. Connect the 100 MHz REF OUT terminal on the PXIe-5653 to the CLK IN terminal on the PXIe-5622. If your external clock signal frequency is set to a frequency other than 10 MHz, set the NIRFSA_ATTR_REF_CLOCK_RATE attribute according to the frequency of your external clock signal. **PXIe-5667—**Connect the external signal to the PXIe-5653 REF IN connector. Connect the 100 MHz REF OUT terminal on the PXIe-5653 to the CLK IN terminal on the PXIe-5622, and connect the 10 MHZ REF OUT terminal on the PXIe-5653 to the REF/LO IN connector on the PXIe-5694. If your external clock signal frequency is set to a frequency other than 10 MHz, set the NIRFSA_ATTR_REF_CLOCK_RATE attribute according to the frequency of your external clock signal. **PXIe-5668—**Connect the external signal to the PXIe-5653 REF IN connector. Connect the LO2 OUT on the PXIe-5606 to the CLK IN connector on the PXIe-5622. If your external clock signal frequency is set to a frequency other than 10 MHz, set the clock rate parameter according to the frequency of your external clock signal. **PXIe-5694—**Connect the Reference Clock signal to the REF/LO IN connector on the PXIe-5694 front panel. **PXIe-5644/5645/5646, PXIe-5820/5840/5841—**Lock the NI-RFSA device to the signal at the external REF IN connector. **PXIe-5830/5831—**For the PXIe-5830, connect the PXIe-5820 REF IN connector to the PXIe-3621 REF OUT connector. For the PXIe-5831, connect the PXIe-5820 REF IN connector to the PXIe-3622 REF OUT connector. For the PXIe-5830, lock the external signal to the PXIe-3621 REF IN connector. For the PXIe-5831/5832, lock the external signal to the PXIe-3622 REF IN connector. **PXIe-5831/5832 with PXIe-5653—**Connect the PXIe-5820 REF IN connector to the PXIe-3622 REF OUT connector. Connect the PXIe-5653 REF OUT (10 MHz) connector to the PXIe-3622 REF IN connector. Lock the external signal to the PXIe-5653 REF IN connector. **PXIe-5841 with PXIe-5655—**Lock to the signal at the REF IN connector on the associated PXIe-5655. Connect the REF OUT connector on the PXIe-5655 to the PXIe-5841 REF IN connector.
NIRFSA_VAL_PXI_CLK_STR ("PXI_Clk")	**PXI-5661—**NI-RFSA locks the NI-RFSA device to the PXI backplane clock using the PXI-5600. You must connect the PXI 10 MHz connector to the REF IN connector on the PXI-5600 front panel to use this option. **PXIe-5668—**Lock the PXIe-5653 to the PXI backplane clock. Connect the PXIe-5606 LO2 OUT to the LO2 IN connector on the PXIe-5624. **PXIe-5644/5645/5646, PXIe-5663/5663E/5665/5667, PXIe-5694, PXIe-5820/5830/5831/5831/5832 with PXIe-5653/5840/5840 with PXIe-5653/5841/5841 with PXIe-5655—**Lock the device to the PXI backplane clock.
NIRFSA_VAL_CLK_IN_STR ("ClkIn")	**PXI-5661—**This configuration does not apply to the PXI-5661. **PXIe-5663/5663E—**NI-RFSA locks the PXIe-5663/5663E to an external 10 MHz signal. Connect the external signal to the CLK IN connector on the PXIe-5622, and connect the PXIe-5622 CLK OUT connector to the FREQ REF IN connector on the PXI/PXIe-5652. **PXIe-5665—**NI-RFSA locks the PXIe-5665 to an external 100 MHz signal. Connect the external signal to the CLK IN connector on the PXIe-5622, and connect the PXIe-5622 CLK OUT connector to the REF IN connector on the PXIe-5653. Set the NIRFSA_ATTR_REF_CLOCK_RATE attribute to 100 MHz. **PXIe-5667—**NI-RFSA locks the PXIe-5667 to an external 100 MHz signal. Connect the external signal to the CLK IN connector on the PXIe-5622, and connect the PXIe-5622 CLK OUT connector to the REF IN connector on the PXIe-5653. Connect the 10 MHZ REF OUT terminal on the PXIe-5653 to the REF/LO IN connector on the PXIe-5694. Set the NIRFSA_ATTR_REF_CLOCK_RATE attribute to 100 MHz. **PXIe-5668—**Lock the PXIe-5668 to an external 100 MHz signal. Connect the external signal to the CLK IN connector on the PXIe-5624, and connect the PXIe-5624 CLK OUT connector to the REF IN connector on the PXIe-5653. Set the clock rate parameter to 100 MHz. **PXIe-5644/5645/5646, PXIe-5820/5830/5831/5831/5832 with PXIe-5653/5840/5840 with PXIe-5653/5841/5841 with PXIe-5655—**This configuration does not apply.
NIRFSA_VAL_REF_IN_2_STR ("RefIn2")	**PXI-5661, PXIe-5663/5663E/5665/5667/5668, PXIe-5644/5645/5646, PXIe-5820/5830/5831/5831/5832 with PXIe-5653/5840/5841/5841 with PXIe-5655—**This configuration does not apply.
NIRFSA_VAL_PXI_CLK_MASTER_STR ("PXI_ClkMaster")	**PXIe-5831/5832 with PXIe-5653—**NI-RFSA configures the PXIe-5653 to export the Reference clock and configures the PXIe-5820 and PXIe-3622 to use PXI_Clk as the Reference Clock source. Connect the PXIe-5653 REF OUT (10 MHz) connector to the PXI chassis REF IN connector. **PXI-5661, PXIe-5663/5663E/5665/5667/5668, PXIe-5644/5645/5646, PXIe-5820/5840/5841/5841 with PXIe-5655—**This configuration does not apply.
Default Values:

PXIe-5694: NIRFSA_VAL_REF_IN_STR

All other devices: NIRFSA_VAL_ONBOARD_CLOCK_STR

Supported Devices: PXI-5600, PXIe-5601/5603/5605/5606 (external digitizer mode), PXIe-5644/5645/5646, PXI-5661, PXIe-5663/5663E/5665/5667/5668, PXIe-5694, PXIe-5820/5830/5831/5832/5840/5841

Data type	Access	High Level Functions
ViReal64	R/W	niRFSA_ConfigureRefClock

Specifies the Reference Clock rate, in Hz, of the signal present at the REF IN or CLK IN connector. This attribute is only valid when the NIRFSA_ATTR_REF_CLOCK_SOURCE attribute is set to NIRFSA_VAL_CLK_IN_STR, NIRFSA_VAL_REF_IN_STR, or NIRFSA_VAL_REF_IN_2_STR.

Valid Values:

PXIe-5644/5645/5646, PXIe-5601/5663/5663E, PXIe-5694, PXIe-5820/5830/5831/5832/5840/5841—10 MHz

PXIe-5603/5605/5665/5667/5668—5 MHz to 100 MHz, in increments of 1 MHz

PXIe-5841 with PXIe-5655—10 MHz, 100 MHz, 270 MHz, and 3.84 MHz * y, where y is 4, 8, 16, 24, 25, or 32.

Default Value: 10 MHz

Supported Devices: PXI-5600, PXIe-5601/5603/5605/5606 (external digitizer mode), PXIe-5644/5645/5646, PXI-5661, PXIe-5663/5663E/5665/5667/5668, PXIe-5820/5830/5831/5832/5840/5841

Data type	Access	High Level Functions
ViString	R/W	niRFSA_ExportSignal

Specifies a comma-separated list of the terminals at which to export the Reference Clock.

Defined Values:

NIRFSA_VAL_NONE_STR ("None")	The Reference Clock is not exported. This value is not valid for the PXIe-5644/5645/5646.
NIRFSA_VAL_REF_OUT_STR ("RefOut")	Export the clock on the REF IN/OUT terminal on the PXI/PXIe-5652, the REF OUT terminals on the PXIe-5653, or the REF OUT terminal on the PXIe-5644/5645/5646, PXIe-5694, or PXIe-5820/5830/5831/5832/5840/5841.
NIRFSA_VAL_REF_OUT2_STR ("RefOut2")	Export the clock on the REF OUT2 terminal on the PXIe-5652. This value is valid only for the PXIe-5663E.
NIRFSA_VAL_CLK_OUT_STR ("ClkOut")	Export the clock on the CLK OUT terminal on the IF digitizer. This value is not valid for the PXIe-5644/5645/5646 or PXIe-5820/5830/5831/5832/5840/5841.
NIRFSA_VAL_IF_COND_REF_OUT ("IFCondRefOut")	Export the clock on the REF OUT terminal on the PXIe-5694. This value is valid only for the PXIe-5667.
Default Value: "" (empty string)

Supported Devices: PXIe-5644/5645/5646, PXI-5661, PXIe-5663/5663E/5665/5667/5668, PXIe-5694, PXIe-5820/5830/5831/5832/5840/5841

Data type	Access	High Level Functions
ViReal64	R	N/A

Returns the actual frequency, in hertz (Hz), of the digitizer Sample Clock.

Units: hertz (Hz)

Supported Devices: PXIe-5668

Data type	Access	High Level Functions
ViString	R/W	None

Specifies the source of the Sample Clock timebase, which is the timebase used to control waveform sampling.

Defined Values:

NIRFSA_VAL_ONBOARD_CLOCK_STR	The digitizer uses its onboard clock as the Sample Clock timebase.
NIRFSA_VAL_CLK_IN_STR	The digitizer uses the signal present on the CLK IN connector as the Sample Clock timebase.
NIRFSA_VAL_DOWNCONVERTER_LO2_OUT_STR	The digitizer uses the signal present on the LO2 OUT connector on the downconverter as the Sample Clock timebase. This value is supported only for the PXIe-5668.
NIRFSA_VAL_LO_REF_CLK_STR	The digitizer uses the signal generated on the 100 MHz REF OUT terminal on the PXIe-5653 as the Sample Clock timebase. This value is supported only for the PXIe-5665.
NIRFSA_VAL_PXI_STAR_STR	The digitizer uses the signal present at the PXI star trigger line as the Sample Clock timebase. This value is not supported for the PXIe-5668.
Default Value: NIRFSA_VAL_ONBOARD_CLOCK_STR

Supported Devices: PXI-5661, PXIe-5663/5663E/5665/5667/5668

Data type	Access	High Level Functions
ViReal64	R/W	N/A

Specifies the frequency, in hertz (Hz), of the external clock used as the timebase source if you set the NIRFSA_ATTR_DIGITIZER_SAMPLE_CLOCK_TIMEBASE_SOURCE attribute to an external source, such as NIRFSA_VAL_CLK_IN_STR, NIRFSA_VAL_LO_REF_CLK_STR, or NIRFSA_VAL_DOWNCONVERTER_LO2_OUT_STR.

**PXI-5661—**If this attribute is set to a value less than 60 MHz, signals at frequencies just above the 20 MHz passband of the downconverter may be aliased back into the passband. This aliasing occurs because the IF frequency of the downconverter is 15 MHz, and the upper end of the passband is 25 MHz. At sampling rates below 60 MHz, the Nyquist frequency is close to the end of the passband and creates aliases that are not filtered effectively by the downconverter.

Units: hertz (Hz)

Valid and Default Values:

Device	Valid Values	Default Value
PXI-5661	Any frequency ≥52.5 MHz	100 MHz
PXIe-5663/5663E/5665/5667	150 MHz	150 MHz
PXIe-5668	2 GHz	2 GHz
Supported Devices: PXIe-5644/5645/5646, PXI-5661, PXIe-5663/5663E/5665/5667/5668

Data type	Access	High Level Functions
ViString	R/W	niRFSA_ConfigurePXIChassisClk10

Specifies the signal to drive the 10 MHz Reference Clock on the PXI backplane. This option can be configured only when the PXI-5600 is installed in Slot 2 of the PXI chassis.

Defined Values:

NIRFSA_VAL_NONE_STR ("None")	The device does not drive the PXI 10 MHz backplane Reference Clock.
NIRFSA_VAL_ONBOARD_CLOCK_STR ("OnboardClock")	The device drives the PXI 10 MHz backplane Reference Clock with the PXI-5600 onboard clock. You must connect the 10 MHz OUT connector to the PXI 10 MHz I/O connector on the PXI-5600 front panel to use this option.
NIRFSA_VAL_REF_IN_STR ("RefIn")	The device drives the PXI 10 MHz backplane Reference Clock with the reference source attached to the PXI-5600 FREQ REF IN connector. You must connect the 10 MHz OUT connector to the PXI 10 MHz I/O connector on the PXI-5600 front panel to use this option.
Default Value: N/A

Supported Devices: PXI-5600 (external digitizer mode), PXI-5661

Related Topics

System Reference Clock

Data type	Access	High Level Functions
ViString	R/W	N/A

Specifies the terminal at which to export the Digitizer Sample Clock.

Valid Values: "" (empty string), "ClkOut"

Default Value: "" (empty string)

Supported Devices: PXIe-5668