Where Does WinCC Runtime Get Its Displayed Time?

WinCC Runtime displays time using the Windows clock of the relevant OS computer, interpreted through the project's configured time basis and any object-specific time setting. This display setting does not synchronize server and client clocks. In the reported PCS 7 V9.0 SP2 / WinCC V7.4 SP1 project, inspect both the computer's Runtime time-basis setting and the Windows/domain time source; having no configured WinCC time master does not by itself establish that each computer has no other clock source.

What the Runtime time display means

Three separate items matter: the computer's current system clock, the time basis used to render time in Runtime, and the mechanism that disciplines clocks across computers. A display option such as local time or UTC changes how a timestamp is shown; it is not itself a clock synchronization service. Siemens documents the WinCC V7.4 LAN time-synchronization feature as synchronizing a client from a connected WinCC server, specified computers, or an external component. That synchronization feature is distinct from choosing a display basis.

Check the project display basis

For a WinCC project, inspect the relevant OS computer object in WinCC Explorer and open its Computer Properties. On the Parameters tab, review the field named “Time basis for time display in Runtime” (exact availability or wording can vary with product release). The setting is a display default for objects on that computer, with possible object-level exceptions. Siemens' later WinCC “Working with WinCC” manual documents the Computer > Properties > Parameters procedure and explains this scope; because the target project is WinCC V7.4 SP1, confirm the exact choices in its installed version's help before changing the project. If the project was migrated, do not assume a migrated-project/server time basis without checking the actual selection.

Check the clock and its authority on each computer

On each OS server and client, inspect the Windows date, time, time zone, and whether the clock agrees with the plant's intended reference.
On domain-joined computers, ask the Windows/domain administrator which source the domain hierarchy uses and whether the OS stations are synchronized to it. A domain-controlled network can distribute Windows time even if PCS 7's WinCC Time Synchronization editor is not configured; the phrase “no time master” may refer only to the PCS 7 design or may indicate a genuine absence of a plant reference. Establish which meaning applies before making changes.
Compare one known event or clock reading across stations, accounting for configured time zones and UTC/local display. Different displayed values can arise from different display bases or unsynchronized clocks; the display alone does not identify the cause.

Inspect WinCC time synchronization separately

In the WinCC V7.4 Options for Process Control documentation, the Time Synchronization editor supports LAN arrangements in which a client imports time from a connected WinCC server, permanently defined computers, or an external component. Siemens states that UTC is used as the base for this LAN synchronization and local-zone display is applied when needed. Inspect each station's existing Time Synchronization configuration and the selected role/source before concluding no synchronization exists. Do not add a second authority merely to make displayed values match: reconcile the PCS 7 design with the existing Windows domain time hierarchy and site requirements first.

Choose a correction path only after diagnosis

If timestamps are consistently offset by a time-zone amount while the underlying clocks agree, investigate the Runtime display-basis and any object-specific setting. If station clocks drift from one another, investigate the active Windows or WinCC synchronization authority and its network reachability. If all clocks agree with each other but not with the required plant reference, the clock hierarchy lacks or is not receiving the intended reference. The PCS 7 V9.0 SP2 Time Synchronization manual describes UTC as the common time base for distributed PCS 7 plants; the applicable plant design and operating requirements must determine whether and how to configure that architecture.

Verification

After inspection or an approved change, compare the Windows clock and time zone on each OS station with the intended source, then compare the same Runtime timestamp on server and client. Confirm whether the displayed difference is a time-zone conversion or a clock offset. Check a relevant alarm or process event timestamp as well as a visible clock, since one display control may have an object-level time basis. Siemens' later WinCC manual notes that changing the project time basis may require reselecting the corresponding picture or report to refresh its display; verify refresh behavior for the installed V7.4 SP1 version.

Limitations and Operational Precautions

The source does not identify the attachment's selected time-basis value, the Windows domain time hierarchy, or whether WinCC/Options for Process Control time synchronization is installed and configured. Therefore it cannot establish which source currently disciplines these stations. The exact project time-basis procedure cited below comes from later WinCC documentation, so use WinCC V7.4 SP1's installed help for release-specific options. Clock changes and time-synchronization changes can affect event ordering and time-stamped records; coordinate them with the control-system owner, domain administrator, and site procedures. Do not set clocks independently or create competing masters.

Engineer FAQ

Does the displayed time come from the PC? Runtime renders time using the station's clock together with the configured time basis. A configured time-synchronization service may discipline that clock from a server, another computer, an external source, or the Windows domain.

Does a missing WinCC time master prove that clocks are unsynchronized? No. It only says that the described WinCC synchronization configuration was not found; Windows domain time or another service may still set the station clocks.

Why can server and client show different times? Check for different actual clocks, time zones, project display bases, and per-object overrides. A display difference alone cannot distinguish these causes.

Should all stations display UTC? PCS 7 V9.0 SP2 documentation recommends UTC as the common basis for distributed PCS 7 plants, but the display policy and system configuration must match the specific plant design and its event-handling requirements.

Technical References

Siemens, SIMATIC HMI WinCC V7.4 – WinCC/Options for Process Control, System Manual, 02/2016, A5E37531976-AA, §4.5, “How to configure the synchronization over the Local Area Network,” pp. 140–141: https://cache.industry.siemens.com/dl/files/231/109736231/att_879839/v1/ProcessControl_en-US.pdf
Siemens, Time Synchronization (V9.0 SP2), Function Manual, 01/2019, A5E39221891-AC, including the rules for distributed PCS 7 plants: https://support.industry.siemens.com/cs/attachments/109767559/ps7tsy_b_en-US.pdf
Siemens, WinCC: Working with WinCC, System Manual, 11/2019, A5E47940912-AA, §1.7.7.2, “How to Set the Time Base in the Project,” p. 140. This is later-version guidance and is cited only for the setting's general scope and inspection path, not as proof that every listed option is present in WinCC V7.4 SP1: https://support.industry.siemens.com/cs/attachments/109773058/WinCC_Working_with_WinCC_en-US_en-US.pdf

Related Tags

WinCC, PCS 7, time synchronization, UTC

Where Does WinCC Runtime Get Its Displayed Time?