• NISCOPE_ATTRIBUTE_INPUT_CLOCK_SOURCE
• NISCOPE_ATTRIBUTE_REF_CLK_RATE
• NISCOPE_ATTRIBUTE_OUTPUT_CLOCK_SOURCE
• NISCOPE_ATTRIBUTE_SAMP_CLK_TIMEBASE_SRC
• NISCOPE_ATTRIBUTE_SAMP_CLK_TIMEBASE_RATE
• NISCOPE_ATTRIBUTE_SAMP_CLK_TIMEBASE_DIV
• NISCOPE_ATTRIBUTE_SAMP_CLK_TIMEBASE_MULT
• NISCOPE_ATTRIBUTE_EXPORTED_SAMPLE_CLOCK_OUTPUT_TERMINAL
• NISCOPE_ATTRIBUTE_CLOCK_SYNC_PULSE_SOURCE
• NISCOPE_ATTRIBUTE_PLL_LOCK_STATUS
• NISCOPE_ATTRIBUTE_OSCILLATOR_PHASE_DAC_VALUE

Data type	Access	Applies to	Coercion	High Level Functions
ViString	R/W	N/A	None	niScope_ConfigureClock

Specifies the input source for the PLL reference clock.

NISCOPE_VAL_NO_SOURCE	("VAL_NO_SOURCE")
NISCOPE_VAL_PFI_1	("VAL_PFI_1")
NISCOPE_VAL_PFI_2	("VAL_PFI_2")
NISCOPE_VAL_EXTERNAL	("VAL_EXTERNAL")
NISCOPE_VAL_CLK_IN	("VAL_CLK_IN")
NISCOPE_VAL_PXI_CLOCK	("VAL_PXI_CLOCK")
NISCOPE_VAL_RTSI_CLOCK	("VAL_RTSI_CLOCK")

Data type	Access	Applies to	Coercion	High Level Functions
ViReal64	R/W	N/A	None	None

If NISCOPE_ATTRIBUTE_INPUT_CLOCK_SOURCE is an external source, this attribute specifies the frequency of the input, or reference clock, to which the internal sample clock timebase is synchronized. The frequency is in hertz.

Data type	Access	Applies to	Coercion	High Level Functions
ViString	R/W	N/A	None	niScope_ConfigureClock

Exports the reference clock to the specified output terminal.

NISCOPE_VAL_NO_SOURCE

NISCOPE_VAL_RTSI_CLOCK

NISCOPE_VAL_PFI_0

NISCOPE_VAL_PFI_1

NISCOPE_VAL_PFI_2

NISCOPE_VAL_CLK_OUT

• Sample Clock
• NI-TClk Overview

Data type	Access	Applies to	Coercion	High Level Functions
ViString	R/W	N/A	None	None

Specifies the source of the sample clock timebase, which is the timebase used to control waveform sampling. The actual sample rate may be the timebase itself or a divided version of the timebase, depending on the NISCOPE_ATTRIBUTE_MIN_SAMPLE_RATE attribute (for internal sources) or the NISCOPE_ATTRIBUTE_SAMP_CLK_TIMEBASE_DIV and NISCOPE_ATTRIBUTE_SAMP_CLK_TIMEBASE_MULT attributes (for external sources).

NISCOPE_VAL_CLK_IN

NISCOPE_VAL_NO_SOURCE

NISCOPE_VAL_PXI_STAR

NISCOPE_VAL_PFI_0

NISCOPE_VAL_PFI_1

VAL_ONBOARD_CONFIGURABLE_RATE_CLK

Data type	Access	Applies to	Coercion	High Level Functions
ViReal64	R/W	N/A	None	None

Specifies, in hertz, the frequency of the external clock used as the timebase source if NISCOPE_ATTRIBUTE_SAMP_CLK_TIMEBASE_SRC is an external source or, if the timebase source is the internal clock for oscilloscopes that support multiple onboard clock rates, of the internal clock.

Data type	Access	Applies to	Coercion	High Level Functions
ViInt32	R/W	N/A	None	None

If NISCOPE_ATTRIBUTE_SAMP_CLK_TIMEBASE_SRC is an external source, specifies the ratio between the sample clock timebase rate and the actual sample rate, which can be slower.

Data type	Access	Applies to	Coercion	High Level Functions
ViInt32	R/W	N/A	None	None

If NISCOPE_ATTRIBUTE_SAMP_CLK_TIMEBASE_SRC is an external source, this attribute specifies the ratio between the NISCOPE_ATTRIBUTE_SAMP_CLK_TIMEBASE_RATE and the actual sample rate, which can be higher. This property can be used in conjunction with the NISCOPE_ATTRIBUTE_SAMP_CLK_TIMEBASE_DIV attribute.

Some devices use multiple ADCs to sample the same channel at an effective sample rate that is greater than the specified clock rate. When providing an external sample clock use this property to indicate when you want a higher sample rate. Valid values for this attribute vary by device and current configuration.

Data type	Access	Applies to	Coercion	High Level Functions
ViString	R/W	N/A	None	niScope_ExportSignal

Exports the sample clock to the specified terminal.

NISCOPE_VAL_NO_SOURCE	("VAL_NO_SOURCE")
NISCOPE_VAL_RTSI_0	("VAL_RTSI_0")
NISCOPE_VAL_RTSI_1	("VAL_RTSI_1")
NISCOPE_VAL_RTSI_2	("VAL_RTSI_2")
NISCOPE_VAL_RTSI_3	("VAL_RTSI_3")
NISCOPE_VAL_RTSI_4	("VAL_RTSI_4")
NISCOPE_VAL_RTSI_5	("VAL_RTSI_5")
NISCOPE_VAL_RTSI_6	("VAL_RTSI_6")
NISCOPE_VAL_PXI_STAR	("VAL_PXI_STAR")
NISCOPE_VAL_PFI_0	("VAL_PFI_0")
NISCOPE_VAL_PFI_1	("VAL_PFI_1")
NISCOPE_VAL_CLK_OUT	("VAL_CLK_OUT")

• Sample Clock
• NI-TClk Overview
• Reference Clock/Phase-Lock Loop

Datatype	Access	Applies to	Coercion	High Level Functions
ViString	R/W	N/A	None	niScope_ConfigureClock

Specifies the line on which the sample clock or the one-time sync pulse is sent or received. This line should be the same for all devices to be synchronized.

NISCOPE_VAL_NO_SOURCE

NISCOPE_VAL_RTSI_0

NISCOPE_VAL_RTSI_1

NISCOPE_VAL_RTSI_2

NISCOPE_VAL_RTSI_3

NISCOPE_VAL_RTSI_4

NISCOPE_VAL_RTSI_5

NISCOPE_VAL_RTSI_6

NISCOPE_VAL_PFI_1

NISCOPE_VAL_PFI_2

• Sample Clock
• NI-TClk Overview
• Reference Clock/Phase-Lock Loop

Data type	Access	Applies to	Coercion	High Level Functions
ViBoolean	RO	N/A	None	None

If TRUE, the PLL has remained locked to the external reference clock since it was last checked. If FALSE, the PLL has become unlocked from the external reference clock since it was last checked.

VI_TRUE

VI_FALSE

• Reference Clock/Phase-Lock Loop

Data type	Access	Applies to	Coercion	High Level Functions
ViInt32	R/W	N/A	None	None

Gets or sets the binary phase DAC value that controls the delay added to the phase-locked loop (PLL) of the sample clock.

Valid Values: [0, 65535]

Default Value: " "

Use this attribute when performing manual adjustment to correct for skew and jitter between oscilloscopes synchronized with NI-TClk.

1. Apply time offset with the niScope_AdjustSampleClockRelativeDelay function.
2. Use this attribute to convert the time offset into a value that can apply the manual adjustment across sessions and improve synchronization repeatability.

For details on performing manual adjustment, refer to Improving NI-TClk Synchronization of Oscilloscopes with Manual Adjustment.

	Note  If this value is set, sample clock adjust and TClk cannot do any sub-sample adjustment of the timebase sample clock.