Syncing PXI Cards to TSN Network

Updated Jun 10, 2021

Reported In

Hardware

  • PXI-6683
  • PXI Synchronization Module

Driver

  • NI-Sync

Issue Details

I have a PXI(e) system and Time Sensitive Networks (TSN) -enabled cRIO or cDAQ controllers . I would like to have a TSN network set up between all of these devices. Can I sync my PXI(e) system to my TSN network?

Solution

Support for TSN or IEEE 802.1AS was added in NI-Sync 19.0 for Linux RT using PXI-6683(H) module. IEEE 802.1AS is not supported on Windows or Pharlap RT. If you are not using Linux RT, see Additional Information section to learn the workaround using IEEE-1588 software time reference.

Soft front panels are not available on Linux RT thus you cannot use NI Measurement & Automation Explorer (MAX) to configure IEEE 802.1AS synchronization. For more information, see NI-Sync Limitations on Linux Desktop and NI Linux Real-Time.

To configure through LabVIEW, refer to shipping example Discipline PXI_Clk10 to Time Reference.vi. The dropdowns currently do not include IEEE 802.1AS. You can modify the polymorphic niSync Set Time Reference.vi to use 802.1AS instance.
DiscipliningClock

If you are using PXI-6683 in the system timing slot of PXI chassis, enable System Timing Slot? in the front panel to override the backplane clock of your chassis with the disciplined oscillator of the PXI-6683.

6683.jpg

Since the PXI-6683H is a hybrid card and does not fit in the timing slot of the chassis, it cannot override the chassis’ backplane directly. Instead, you will need to externally cable the disciplined on-board oscillator of the PXI-6683H to the 10 MHz Ref In connector on the chassis. (Consult your chassis’ user manual to ensure your chassis has a 10 MHz Ref In). Then disable System Timing Slot? in the front panel to override the backplane clock of your chassis with the clock routed externally from PXI-6683H.

6683H.jpg

IEEE 802.1AS related properties can be accessed using niSync Property Node.vi via dropdown Timing >> Time Reference >> 802.1AS. Refer to Target Support for Timing Properties and VIs section from NI-Sync LabVIEW API Help to determine whether or not a given property or VI is supported on Linux RT.

Additional Information

Some PXI cards can accept IEEE-1588 software time references to synchronize their systems, however IEEE-1588 software timed synchronization is not compatible with TSN. To synchronize your TSN and 1588 networks, you can bridge the PXI's 1588 network with the cDAQ/cRIO TSN network by connecting to a cRIO-904X (CompactRIO) or IC-317X (Industrial Controller). 

One Network Interface Card (NIC) on the cRIO or IC syncs to the 1588 software timed synchronization network, and the other NIC syncs to the TSN network. The 1588 network will sync the system clocks of devices on that network and the TSN network will sync the system clock, FPGA clock, and DSA clocks of devices on that network to network time. This setup will automatically determine which clock is the best master for either network through and election process. There is no additional configuration for this; you would just need both the 1588 and the 802.1AS time references installed on the bridge controller using the NI-TimeSync driver 17.5 or newer . 

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