Reading System Time and Date into WinCC TIA Portal Tags

WinCC V7.x exposed system time and date through dedicated system channels that could be dragged directly onto a tag configuration. When projects migrated to WinCC V11 and later (TIA Portal, now at V18/V19), those system channels were removed from the tag editor. Engineers moving a working V7 project to TIA Portal therefore lose the "free" date/time tag and must reconstruct the functionality with a script, an area pointer, or a system diagnostic block. This article documents the field-proven pattern: declare an internal String or Date/Time tag, populate it from a scheduled VBScript (or C-Script), and route that tag into a UserArchive row for time-stamping production events.

1. Problem Definition

The original symptom reported in the field: a user inserts a clock object on a WinCC V11 screen in digital mode, assigns a tag to the Output value property, and the tag reads back as a blank value when read with GetTagChar or GetTagFloat. The clock face animates, but the value the script receives is empty.

Root cause: the clock object is a visual graphic primitive in the TIA Portal graphics designer. It is driven by the runtime's own date/time source; it does not push a value into a connected tag. Assigning a tag to the property only binds a reference for output of an input widget such as an I/O field, not the other way around. To capture the time, you must explicitly write it from script into a tag of compatible data type.

2. Prerequisites

• Siemens TIA Portal V11 SP2 or later (procedure verified through V17/V18; same code applies to V19).
• WinCC Comfort, Advanced, or Professional Runtime license on the HMI panel or PC.
• UserArchives option package installed and licensed if you intend to log the captured time.
• VB scripting or C-scripting enabled in the runtime settings: Runtime settings > Scripts > Allow VB scripts = Yes (Advanced/Professional only — Comfort panels do not support VBScript, use C-Script or a scheduled task with system functions).
• Project compiled and downloaded to the target device or RT simulation.

3. Tag Configuration in TIA Portal

3.1 Internal Tag Declaration

Open the HMI tag editor and create a new tag with the following properties:

For arithmetic processing (compare timestamps, compute duration) declare a second internal tag with data type DateTime. The DateTime type is stored as 8 bytes BCD and is supported on Comfort/Advanced panels and WinCC Professional.

3.2 Area Pointer Alternative (No Script)

If the requirement is only to display the time, configure the HMI area pointer Date/Time under Connections > Area pointers. The PLC can then write the controller time of day (S7-300/400/1500) to the panel. This is not the same as the runtime's local PC time and is not suitable when the time stamp must reflect the operator's local clock for audit purposes.

4. VBScript Solution

The recommended pattern uses a scheduled VBScript that calls the VBScript Time(), Date(), and Now() intrinsic functions and writes the result to the internal String tag. Schedule the script with a 1-second trigger.

4.1 VBScript Source

' VBScript: write system time and date to internal String tags
' Trigger: 1 s cyclic, event-driven, or on a button click

Dim sTime, sDate, sNow

sTime = Time()                ' returns "hh:mm:ss"
sDate = Date()                ' returns "mm/dd/yyyy" (US locale)
sNow  = Now()                 ' returns "mm/dd/yyyy hh:mm:ss"

' Write to internal string tags
SmartTags("TimeStamp_Time").Value = CStr(sTime)
SmartTags("TimeStamp_Date").Value = CStr(sDate)
SmartTags("TimeStamp_Now").Value  = CStr(sNow)

' Optional: parse to Date/Time tag for arithmetic
SmartTags("TimeStamp_DT").Value  = CDate(sNow)

' Optional: ISO-8601 format for sorting and database logging
SmartTags("TimeStamp_ISO").Value = Year(Now) & "-" & _
                                   Right("0" & Month(Now), 2) & "-" & _
                                   Right("0" & Day(Now),   2) & " " & _
                                   Right("0" & Hour(Now),   2) & ":" & _
                                   Right("0" & Minute(Now), 2) & ":" & _
                                   Right("0" & Second(Now), 2)

' Trace output to diagnostics window
HMIRuntime.Trace "Time: " & sNow & vbNewLine

4.2 Trigger Configuration

1. Open HMI tags > [your tag] > Events or create a new VB function under Project tree > Scripts > VB scripts.
2. Right-click the function > Properties > Triggers > add a new trigger.
3. Set trigger type to Cyclic with cycle 1 s (or 500 ms for smoother display).
4. Compile the project and download. Verify the apdiag trace window shows the time string updating every second.

5. C-Script Equivalent

Engineers constrained to C-Scripting (Comfort panels, or legacy code bases) can use the standard ANSI C runtime functions. The tag read/write functions are still GetTagChar, SetTagChar, GetTagFloat, SetTagFloat depending on tag type.

5.1 C-Script Source

/* C-Script: write system time and date to internal tags */
#include <time.h>

void WriteTime(void)
{
    time_t      now;
    struct tm*  t;
    char        buf[32];

    time(&now);
    t = localtime(&now);

    /* Format 1: ISO-8601 with seconds */
    strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M:%S", t);
    SetTagChar("TimeStamp_ISO", buf);

    /* Format 2: just the time */
    strftime(buf, sizeof(buf), "%H:%M:%S", t);
    SetTagChar("TimeStamp_Time", buf);

    /* Format 3: just the date */
    strftime(buf, sizeof(buf), "%d.%m.%Y", t);
    SetTagChar("TimeStamp_Date", buf);

    printf("Time written: %s\n", buf);
}

The reason the original poster saw a blank value with GetTagChar is that the WinCC runtime returns a zero-length string from a tag that was never written to, or returns the tag's declared default (which is empty for a newly created internal String tag). Adding the script as a scheduled event resolves the read-back.

6. Routing the Timestamp into a UserArchive

6.1 UserArchive Column Definition

In the UserArchive configuration, define the time/date column with these properties:

6.2 Inserting a Row with the Timestamp

Use the VBScript HMIRuntime.BaseHMI UserArchive object model. The standard pattern is:

' VBScript: insert a new archive row with current timestamp
Dim ua, row, ret

Set ua = HMIRuntime.BaseHMI.UserArchive("ProductionEvents")

' Build a new row
Set row = ua.Add()

' Populate fields
row.Item("EventTime").Value = SmartTags("TimeStamp_ISO").Value
row.Item("Operator").Value  = SmartTags("CurrentOperator").Value
row.Item("PartNumber").Value = SmartTags("PartNumber").Value
row.Item("Result").Value    = SmartTags("Result").Value

' Commit to the archive (writes to disk and ring buffer)
ret = row.Write()

If ret <> 0 Then
    HMIRuntime.Trace "UserArchive write failed: " & ret & vbNewLine
End If

' Optional: clean up the row object
Set row = Nothing
Set ua  = Nothing

Trigger this script from the same button that logs the production event. The 1-second cyclic refresh of TimeStamp_ISO guarantees that the value written into the archive is no more than one second stale at the moment the button is pressed.

7. Scheduled Event vs. Button-Triggered Event

There are three common trigger points for the timestamp script:

8. Display on a Screen

Drop an I/O field on the screen, set Mode to Output, set the Tag to TimeStamp_ISO, and configure the Format property to yyyy-MM-dd HH:mm:ss. The field will display whatever the script most recently wrote.

For the date/time to update visually without page refresh, the underlying tag must have its Update cycle set, and the I/O field property Refresh set to Visible. The WinCC digital clock object already handles this; pairing it with the I/O field driven by the script is the standard solution.

9. Troubleshooting Matrix

10. Synchronization with PLC Time

If the PLC is the master clock (typical in S7-1500 projects with T_CONFIG time synchronization), the HMI should display the controller time, not the panel local time. Configure an area pointer of type Date and Time from the PLC to the HMI, and the HMI displays the S7-1500 time-of-day. For logging in a UserArchive on the HMI side, read the same S7 clock with:

' VBScript: read PLC time from area pointer tag
Dim sPlcTime
sPlcTime = SmartTags("PLC_Date_And_Time").Value
SmartTags("TimeStamp_ISO").Value = sPlcTime

The PLC tag must be of type DTL (S7-1500) or DT (S7-300/400) and is automatically populated by the area pointer configuration under Connections > Area pointers > Date and Time.

11. Performance and Memory Considerations

Writing one String tag of length 24 bytes once per second consumes a negligible share of the runtime's tag update bandwidth. The trace output to the diagnostics window, however, is more expensive: HMIRuntime.Trace writes to a ring-buffered log file, and on a Comfort panel the flash memory has a finite write endurance. Recommendations:

• Enable trace only during commissioning; disable for production release.
• Avoid writing the timestamp string more frequently than the screen update rate (typically 1 Hz for analog clock visuals).
• For a UserArchive that records every second, configure the archive's Data record length and ring buffer to match the retention requirement (e.g. 86 400 rows for 24 h at 1 Hz).

12. Verifying the Implementation

1. Compile and download the project to the target HMI or RT PC.
2. Start runtime; open the diagnostics window (Start > SIMATIC > WinCC > Diagnostics).
3. Confirm Trace shows the timestamp string updating once per second.
4. Insert a test row into the UserArchive via the VBScript button; export the archive to CSV and confirm the EventTime column contains ISO-8601 strings in the expected sequence.
5. Force a runtime restart; verify the cyclic script resumes and the tag value repopulates within one cycle (≤ 1 s).
6. Disconnect network and reconnect; verify the script continues to run (no dependency on the PLC connection for the local-time case).