Time zone settings

To interact with devices located in different time zones, the system converts any alarm/waveform timestamp and the actual time sent within the Set Time command from / to the local time zone. The Windows time zones database is used to take daylight saving time into account. Thus, time zone names must be taken directly from this database (case-insensitive), otherwise the system will default to the I/O Server’s local time zone. The Windows time zone database is in the Windows registry in HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones\. Examples of time zone names are:

  • AUS Central Standard Time
  • China Standard Time
  • Pacific Standard Time (Mexico)

Device time zones can be specified on two levels:

  1. Use section [ProtocolName.ClusterName.PortName.IODeviceName] to specify the time zone for a particular device.

    For example:

    [PLOGIC870.Cluster1.PM870_Port.PM870_Device1]
    Time zone = Singapore Standard Time

  2. Use general section [POWERLOGICCORE] to specify the time zone for all devices.

    For example:

    [POWERLOGICCORE]
    Time zone = Mountain Standard Time

The device-specific time zone specification takes precedence. In other words, if both examples are present in the Citect.ini file, the PM870_Device1 would be located in “Singapore Standard Time” time zone, and all the other I/O devices in the project would be located in “Mountain Standard Time” time zone.

If there is no time zone specification, or if it does not match the time zone from Windows database, the device would be in the same time zone as the machine where the I/O Server is running; thus, no time conversion will occur.

If only the first of the previous examples is present within the Citect.ini file, the PM870_Device1 would be located in “Singapore Standard Time,” and all the other devices would use the current local time zone.