TimeSync for SNTP: Getting Started

[meggert@NI]

SNTP Time Reference (Labs): http://ftp.ni.com/support/softlib/Timing_Sync/Labs/NI-TimeSync/NITimeSync1_2_d15.exe

Description:  The NI-TimeSync SNTP Time Reference allows you to synchronize your LabVIEW RT (VxWorks/PharLAP) system time to an SNTP server.

Installation Instructions:

    * Run the self extracting exe
    * Update your target through MAX to install the new software available

Selecting the SNTP server to synchronize to:

    * modify the following line in the file "/ni-rt/system/ni-timesync/ni-timesync-sntp.ini"
          o source.sntp.address = IP_ADDRESS_OF_SNTP_SERVER

[joergh]

Hi, I just wanted to configure a PXI-RT controller to sync from NTP (LV2011SP1f1), but it still had no option for this. So I installed NI TimeSync (1.3) but again - no luck. Then I remembered this community page - but this seems to be for NI TimeSync 1.2. So, is there ANY possibility to sync to a (S)NTP time source? Will this plugin be upgraded?

Thanks,

     Jörg

[joergh]

Answering my own comment: I just installed the version 1.2d15 from above onto a PXI controller running LabVIEW 11.0.1f1, and followed the instructions and it worked.

[hrobitaille]

HI,

We are using the NI TimeSync with VeriStand.

VeriStand stops to run if the drift is too high (for example, if we restart the NTP server).

Is there a way to specify to NI TimeSync the maximum drift to apply at a time to the system time ?

What is the timekeeperSynchronizationThreshold ?

Thanks,

Hubert

[meggert@NI]

Hi Hubert,

There is not a programmatic way to control the amount of correction we apply to the system time.  timeKeeperSynchronizationThreshold is a value you can set to control the amount of time (in seconds) you can be "off" from your time source (SNTP) and our plugin will still consider itself synchronized.  The default value is .01 or 10ms.

Can you please explain further what exactly is stopping inside of Veristand?  Is there an application you are running that is sensitive to changes in time? If so, what exactly is it sensitive to?

Unfortunately, with a software synchronization solution (i.e. no hardware stability from an OCXO/TCXO) we have imperfect holdover ability.  In order for us to prevent this we need to have a more stable time reference to peg ourselves against.  Is there a way you can prevent the SNTP server from restarting?  Alternatively, if time reference (SNTP) stability is an issue, you might consider running several nodes on the system that are capable of mastering a PTP network, in which case failover of any one node would not cause loss of synchronization.  You would just use the PTP plugin for NI-TimeSync instead and all the nodes should still synchronize correctly to the "best clock" on the network.

Sincerely,

Mark Eggert

[hrobitaille]

Hello Mark,

Our problem is not with the stability of the clock, but with the initial difference between the 2 time sources : external and .

As we have a request to be able to run if we are connected or not to the time server, we don't know when the first synchronization could happen and which drift we could have between the 2 times.

About VeriStand, it is directly the Primary Control Loop which stops : "error code: -307732 NI VeriStand : The system has become unresponsive. The primary control loop has been shut down".

I suppose there is a check on the system time difference between 2 loops in the PCL.

In some case, we have seen this problem too using PTP between 2 PXI systems : when both systems are running, if we power-off / power-on the system which has been configured as the PTP master clock, the second system can stop with the error -307732.

Regards,

Hubert

[drich]

Hey Hubert,

That error code is due to the time change between the systems. Veristand by default has a watchdog timer that makes sure the system hasn't hung and in this case that timer is incorrectly firing since the system time has changed.

http://zone.ni.com/reference/en-XX/help/372846D-01/veristand/vs_error_codes/

As that page mentions there should be a way to disable that error so that the watchdog won't fire. To do that

"To correct this error, enable the Filter Watchdog Errors checkbox on the Controller Configurationpage of the System Explorer window. You can configure watchdog functionality by monitoring the Watchdog Timer system channel using alarms and procedures"

Hopefully that will solve your problem.