How Can I Synchronize Multiple DSA Devices with Traditional DAQ?

These two example programs illustrate synchronization between an arbitrary number of Dynamic Signal Acquisition (DSA) devices and measure the phase difference between the first channels of each board. The phase difference shows how closely the boards are synchronized based on a common input signal. The indicator at the bottom of the screen displays the measured phase mismatch (in degrees) for the sine signal. This value should be considerably less than one degree. A low phase mismatch indicates tight synchronization between boards. For example, the phase mismatch specification for multiple 4472s is 0.1 degree when acquiring a 1 kHz sine tone.

This document includes two separate example VIs. The first VI is for use with multiple PXI-4472s. The second VI is for synchronizing two or more PCI DSA devices (4472, 445x, or 455x). If you are using the PCI version, connect the trigger/clock lines with a RTSI cable. The PXI bus has built-in signal connections on the backplane, so you don't need to add external connections for multi-board synchronization. The PXI 4472 shares its clock signal along the length-matched Star Trigger bus to minimize the interchannel delay.

Each VI is set up to accept an arbitrary number of slave devices. Depending on the bus factor, it will configure the triggering and clocks accordingly.

Perform the following steps to set up the PCI-4472, 445x, or 455x.
1) Install the PCI DSA boards.
2) Connect the boards with the RTSI cable. (PCI boards only)
3) Connect the sine source to channel 0 of both DSA boards.
4) Set the device numbers and slave device numbers appropriately.

Perform the following steps to set up the PXI-4472.
1) Install one of the DSA boards in Slot 2 of the PXI chassis.
2) Connect the sine source to channel 0 of both DSA boards.
3) Set the device numbers and slave PXI slot numbers appropriately. If the slot number is incorrect, the slave board will not receive a clock signal and the acquisition will time out.

If you are using PXI-4472 devices, verify that the master device is recognized as being in slot 2 of the chassis in Measurement & Automation Explorer.

The NI-447x and NI-446x devices can be synchronized using DAQmx which is the preferred method. See the link below for examples.

Related Links:

Synchronizing DSA Devices in DAQmx

Sound and Vibration Homepage

Requirements

Filename: 4472_synchronization__pci_.llb

Software Requirements

Application Software: LabVIEW Full Development System 6.1
Language(s): LabVIEW

Hardware Requirements

Hardware Group: Dynamic Signal Analyzers (DSA)
Hardware Model: PCI-4452, PCI-4472, PXI-4472, PCI-4551, PCI-4552, PCI-4451
Driver: Traditional NI-DAQ (Legacy) 6.9.1

Filename: 4472_synchronization__pxi_.llb

Software Requirements

Application Software: LabVIEW Full Development System 6.0
Language(s): LabVIEW

Hardware Requirements

Hardware Group: Dynamic Signal Analyzers (DSA)
Hardware Model: PCI-4472, PXI-4472, PCI-4551, PCI-4552, PCI-4451, PCI-4452
Driver: Traditional NI-DAQ (Legacy) 6.9.0, Traditional NI-DAQ (Legacy) 6.9.1

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