PLC as NTP server for local subnet

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1

Hi Everyone
I’m trying to use a APC2200 as a NTP server for all the other systems inside the machine local network.
My issue is with the computer (a Win 10 panel pc from B&R) that seems not to like the PLC NTP for some reason.

Inside the PLC configuration I only enabled the NTP (not that there are other parameter to configure that I’m aware of)

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This is what the CMD return from the client computer

C:\Windows\system32>w32tm /query /configuration
[Configuration]

EventLogFlags: 2 (Local)
AnnounceFlags: 5 (Local)
TimeJumpAuditOffset: 28800 (Local)
MinPollInterval: 10 (Local)
MaxPollInterval: 15 (Local)
MaxNegPhaseCorrection: 54000 (Local)
MaxPosPhaseCorrection: 54000 (Local)
MaxAllowedPhaseOffset: 1 (Local)

FrequencyCorrectRate: 4 (Local)
PollAdjustFactor: 5 (Local)
LargePhaseOffset: 50000000 (Local)
SpikeWatchPeriod: 900 (Local)
LocalClockDispersion: 10 (Local)
HoldPeriod: 5 (Local)
PhaseCorrectRate: 1 (Local)
UpdateInterval: 360000 (Local)


[TimeProviders]

NtpClient (Local)
DllName: C:\Windows\SYSTEM32\w32time.DLL (Local)
Enabled: 1 (Local)
InputProvider: 1 (Local)
AllowNonstandardModeCombinations: 1 (Local)
ResolvePeerBackoffMinutes: 15 (Local)
ResolvePeerBackoffMaxTimes: 7 (Local)
CompatibilityFlags: 2147483648 (Local)
EventLogFlags: 1 (Local)
LargeSampleSkew: 3 (Local)
SpecialPollInterval: 32768 (Local)
Type: NTP (Local)
NtpServer: 192.168.10.10,0x9 (Local)

NtpServer (Local)
DllName: C:\Windows\SYSTEM32\w32time.DLL (Local)
Enabled: 0 (Local)
InputProvider: 0 (Local)



C:\Windows\system32>w32tm /query /source
Local CMOS Clock

C:\Windows\system32>w32tm /monitor /computers:192.168.10.10
192.168.10.10[192.168.10.10:123]:
    ICMP: 0ms delay
    NTP: -3595.6371045s offset from local clock
        RefID: (unknown) [0x00017F7F]
        Stratum: 15

Warning:
Reverse name resolution is best effort. It may not be
correct since RefID field in time packets differs across
NTP implementations and may not be using IP addresses.

C:\Windows\system32>w32tm /stripchart /computer:192.168.10.10
Tracking 192.168.10.10 [192.168.10.10:123].
The current time is 3/26/2025 2:37:40 AM.
02:37:40, d:+00.0008887s o:-3595.6366829s  [@                          |                           ]
02:37:43, d:+00.0010423s o:-3595.6364313s  [@                          |                           ]
02:37:45, d:+00.0005041s o:-3595.6361420s  [@                          |                           ]
02:37:47, d:+00.0007006s o:-3595.6366132s  [@                          |                           ]
^C
C:\Windows\system32>w32tm /resync /rediscover
Sending resync command to local computer
The computer did not resync because no time data was available.

C:\Windows\system32>

I’ve already tried to do the unregister/register and manual reconfig of the NTP server inside the CMD, no matter of what I’ve found online to try on this machine, Windows will remain synched with the CMOS Clock.

Any idea on what to edit in order to synkcronize the time and date of the PC to the PLC?

2

According to your screenshot the “stratum” is 14 which is one of the lowest (aka “unprecise”) time values.
I doubt that Windows will accept such a low value

Please try to set a lower stratum (which will then tell the NTP client that the time is more precise)
I would suggest to use a value of 3 to 5 to test

In general the stratum tells a client how many servers are between the atomic world clock and its previous sender. 14 would mean that there are 13 other “client/servers” in between and I assume this is too worse for any Windows PC

2 Likes
3

Thanks a lot, I’ve completely ignored that parameter, thinking that was a Windows issue.
Now it works perfectly!

1 Like
4

Perfect :slight_smile: great to hear !
Thanks for the feedback