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Entry type: FAQ, Entry ID: 22144502, Entry date: 03/12/2014
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How do you configure your PC as NTP server?

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The Network Time Protocol (NTP) is a standard for synchronizing computer system clocks over package-based communication networks.

Although this is usually done via UDP, it can also be transported by other Layer 4 protocols such as TCP, for example. It was specially developed to enable reliable time relaying over networks with variable package runtimes.

The Simple Network Time Protocol (SNTP) is a simplified version of NTP. It is described in RFC 2030. The Network Time Protocol (NTP) is described in RFC 958.

Instructions for Windows 2000, Windows XP, Windows Server 2003 and Windows Server 2008 (32-bit)
Follow the instructions to configure your local PC as NTP server. In this way you can synchronize other devices with the local PC.

  1. Open the registry editor via "Start > Run... > regedit".
  2. Search for the code
    "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Parameters".
  3. Set the "LocalNTP" value to 1.
     

    Fig. 01

    Note

    • If the "LocalNTP" value does not exist in your system, create a new DWORD value.

    • The value 0 means disabled, 1 means enabled

  4. Restart the computer to make the changes effective.


Procedure for Windows 7 (32-bit and 64-bit), Windows Server 2008 R2 (64-bit) and 2012 R2 (64-bit)
Follow the instructions to configure your local PC as NTP server. In this way you can synchronize other devices with the local PC.

  1. Stop the "Windows Time" service under Start > Control Panel > System and Security > Administrative Tools > Services.
     

    Fig. 02
  2. Open the registry editor via "Start > Run... > regedit".
  3. Search for the code "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\W32Time\TimeProviders\NtpServer".
  4. Set the "Enable" value to 1.


    Fig. 03
  5. Search for the code
    "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\W32Time\Config".
  6. Set the "AnnounceFlags" value to 5.
     

    Fig. 04
  7. Start the "Windows Time" again and set the start type to "Automatic".
     
Note
When using the Windows server 2012 R2 (64-bit), after Step 7 you have to set the start type to "Automatic (Delayed Start)" for the service to start automatically.
The instructions below are for configuring the Windows Time service when using an internal hardware clock and an external time source:
Windows operating systemInstructions
Windows 2000https://support.microsoft.com/help/216734
Windows XPhttps://support.microsoft.com/help/314054
Windows Serverhttps://support.microsoft.com/help/816042

If the firewall is enabled, it must be configured to permit external access to Port 123. This is necessary because the time server service expects external request messages.

Warning
Changes in the Registry might lead to unexpected problems requiring you to reinstall your system. We cannot guarantee that problems arising from changes in the registry can be solved. Changes in the Registry are made entirely at the user's own risk.


Security information
In order to protect plants, systems, machines and networks against cyber threats, it is necessary to implement – and continuously maintain – a holistic, state-of-the-art industrial security concept. Siemens’ products and solutions constitute one element of such a concept. For more information about industrial security, please visit
http://www.siemens.com/industrialsecurity.