DST and PI 3

It is essential that the date, time, and time zone settings on the PI 3 Server node are correct for proper handling of DST transitions.

• Check your computer’s date and time settings:

On Windows:

1. Open the “Date and Time” control panel and verify the date and time.
2. Select the “Time Zone” tab and make sure the proper time zone region is selected. 
3. If DST is observerd in your time zone, select the “Automatically adjust for daylight saving changes” check box .

On Unix:  Type "date" and press Enter at a command prompt.  If the correct settings are not listed, then use the date/time utility for your flavor of UNIX to adjust the settings.

• Verify your localhost.tz settings
  
  On Windows:
  
  
  1. Open a command prompt and change to the pi\adm directory.
  2. Type the following command and press Enter:
  
          pidiag -tz -dump -brief
  
  This will list a rule for every year from 1970-2038.
  
  If you are in the U.S.A, Canada, or New Zealand and observe DST, you should see a change in the DST month from 2006 to 2007. For example, here is a snippit of the the U.S.A./Canada localhost.tz file settings showing that now DST changes in March and November instead of April and October:
  
  2005,"03-Apr-2005 02:00:00 S","30-Oct-2005 02:00:00 D"
  2006,"02-Apr-2006 02:00:00 S","29-Oct-2006 02:00:00 D"
  2007,"11-Mar-2007 02:00:00 S","04-Nov-2007 02:00:00 D"
  2008,"09-Mar-2008 02:00:00 S","02-Nov-2008 02:00:00 D"
  
  If your country's DST rules have changed recently, see KB # 2341OSI8.
  
  
• Make sure the operating system’s TZ environment variable is not set on the server.

On Windows systems, the Windows TZ variable (not to be confused with the PI localhost.tz file) overrides your DST/ST rules and can cause some programs to get the wrong UTC time. To see if the Windows TZ variable is set, type "set" at a command prompt and press Enter.  If you see a "TZ" setting, then follow these steps to clear the setting:

1. Open the System Properties control panel.
2. Bring forward the Advanced tab.
3. Click on Environment Variables.
4. Select the TZ variable and choose "Delete."

It is important that all interfaces sending data to the PI Server are also correctly configured in order for incoming data to be properly stored.  Please read the DST and Interfaces page for issues that may affect your PI 3 system during a DST transition.

• Using the TZ environment variable on your operating system might cause problems during DST/ST transitions. Please read the TZ section above for how to check the settings and clear them if necessary.
• If you are running PI version 3.2.357.x and earlier and using the PI Totalizer, please see the Support Solution # 809OSI8 on a known problem with Totalizers during DST transition.
• If you are running PI version 3.2.357.8 and earlier, there is a known DST bug where performance equations will be off by one hour until PI is stopped and restarted. See Support Solution # 900OSI8.
• Check the DST and Clients page for issues specific to how clients view data from the PI 3 Server.
• PI 3.2 Servers have a known problems during DST. They return PI local time for pitm_servertime calls adjusted from 0 to 59 minutes after a time change occurs on the server. This means that events coming in to the server may have incorrect time stamps for up to 59 minutes. This affects all interfaces that are not using the /PISDK=1 flag in their startup files. 
• UNIX users should be aware that date and time settings can be configured for an individual login as well as for the entire system. If experiencing problems, check the settings for the user logging into the system and make sure they do not differ from the system's settings. Customers can check in the ~/.login and ~/.profile files for their login account. For example, "cat ~/.profile | grep TZ" will echo out any local user settings.