Forms of Device Synchronization

The following forms of synchronization are available, listed in order by synchronization accuracy.

Note  Synchronization accuracy specifications depend on the system and device(s) being used. Refer to your device Specifications for more information.

Note  Sharing a clock (reference clock or sample clock) among devices can achieve time locking. In some cases, time locking among clocks can achieve greater determinism; however, it does not affect any overall delays in signals sent.

Software-Based Synchronization

You can send a synchronization software command from a host computer to a device. Synchronizing events by software is not deterministic on operating systems such as Windows or Mac.

• Accuracy: tens of milliseconds

Related Topics

Supported Synchronization Methods by Device

Time-Based Synchronization

Note  You can use a time-based protocol, such as GPS, 1588, or IRIG-B, to coordinate events at large distances, typically greater than 10 m.

• Accuracy: under 100 nanoseconds

Related Topics

Introduction to NI Clock Disciplining for PXI Express

PXI_Clk10 Disciplining and Synchronization across Multiple PXIe Chassis

Timing and Synchronization Systems

Synchronization Products

Signal-Based Synchronization

PXI Trigger or RTSI Trigger Routing (SCOPE, FGEN, HSDIO, RF)

You can send an electrical signal from one device (master) to another (slave) to signal an event using the trigger routing available from a PXI chassis or RTSI cable. The devices dictate the level of determinism. The signal path length mainly determines the synchronization accuracy.

• Accuracy: tens of nanoseconds

Related Topics

Synchronization Explained (trigger routing and sharing clocks and triggers)

Triggers Offered by PXI Standard

PXI Star Trigger Line

External Triggering

Note  In this case, external refers to triggering external to your PXI chassis or external to the device for other device form factors, for example USB and PCIe.

You can send triggers to each device through PFI, channel, or other I/O lines on the device front panel. When trigger lines have matched signal path lengths, measured synchronization results may improve.

• Use time locking for greater determinism.
• Accuracy: ± 1 sample clock

Related Topics

Improving System Clock Error

When to Use External Sample Clock

NI-TClk (SCOPE, FGEN, HSDIO, RF)

You can use NI-TClk to programmatically phase align clocks and coordinate triggers between devices and multiple chassis. NI-TClk is an advanced synchronization method, and is not supported by all devices.

• Use time locking for greater determinism.
• Accuracy: 10-500 ps

Related Topics

National Instruments T-Clock Technology for Timing and Synchronization of Modular Instruments

Supported Synchronization Methods by Device