How To Use Windows 7 As SNTP Timeserver


Many Omron PLC's with Ethernet supports auto adjustment of the clock by using SNTP. This requires a computer with a running NTP Server. In Windows 7, the NTP Server uses a "Authoritative Time Server", which requires authentication.


The NTP server needs to be enabled without using "Authoritative Time Server" in order to work without authentication. Follow these steps to properly setup the server:

  • Open a CommandPrompt as Administrator.
  • Run the command "regedit"
  • Change HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config\AnnounceFlags to "5"
  • Change HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpServer\Enabled to "1"
  • Change HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\VMICTimeProvider\Enabled to "0"
  • Close regedit.
  • Run the command "net stop w32time"
  • Run the command "net start w32time"
  • Close the CommandPrompt. 

More info on the windows timer server can be found at microsoft :