Clock 10 Discipline Add-On for NI VeriStand

Publish Date: Sep 30, 2013 | 1 Ratings | 5.00 out of 5 |  PDF

Overview

The Clock 10 Discipline add-on for NI VeriStand enables users to discipline the backplane (CLK 10) of their PXI Chassis to an external time reference. This add-on uses two timing and synchronization cards. A PXI-6653 performs the backplane dicipline and a PXI-6682 captures the external time reference. This process reduces the jitter on the PXI backplane and synchronizes the 10 MHz backplane clock with an external time reference.

This add-on is considered legacy and is no longer updated. A better add-on named the Chassis TimeSync custom device is available here: https://decibel.ni.com/content/docs/DOC-29546

The Clock 10 Discipline add-on allows you to easily discipline your PXI chassis backplane with an external time reference input using NI VeriStand.  With this add-on you will be able to discipline your PXI backplane to any of the accepted input time references listed below:

  • IEEE 1588-2008
  • GPS
  • IRIG-B
  • PPS

The Clock 10 Discipline add-on will use an NI PXI-6653 in the Timing slot of your PXI chassis to drive the backplane timing.  You will connect your external time input reference to the NI PXI-6682, and it can be placed in any slot of the chassis.  All communication between the two cards is done in software.  No external connections are required to use this add-on.  You will need to ensure that NI-Sync is installed on your PXI target to use this add-on. The PXI-6653 and PXI-6682H can be purchased together in a discounted PXI Timing and Sync Bundle.

After installing the Clock 10 Discipline add-on, it can be added to the system configuration as a custom device. In order to successfully synchronize the clocks, the timing source input to the NI PXI-6682 must have 1 PPM or better accuracy. The Clock 10 Discipline custom device can be seen in Figure 1.

Veristand Workspace.png
Figure 1

This Clock 10 Discipline custom device has three channels that you can monitor from the NI VeriStand Workspace.  These three channels are Locked?, Lock Lost?, and Offset, and they are described below.

The Offset channel displays the magnitude of the difference between the reference clock and Clock 10 of the PXI backplane.  The Locked? channel tells the user whether the backplane has been successfully synchronized with the external time reference.  In order for the clocks to be locked, the Offset must be less than 20 nS for a period of time greater than 30 seconds.  The Locked Lost? channel indicates when the when the Offset exceeds 20 nS after the clocks have become locked.

There is no user interaction required to use this add-on.  Once you have the correct hardware, you simply install the custom device and run the Workspace.  NI VeriStand will then discipline Clock 10 of your PXI backplane to your external timing source.  You can then add indicators to your Workspace to verify that the clocks have synchronized. 

This add-on is considered legacy and is no longer updated. A better add-on named the Chassis TimeSync custom device is available here: https://decibel.ni.com/content/docs/DOC-29546

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