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Configuring Central NTP Time Synchronization and Legacy System Services in SIMATIC PCS 7 V8.1

Configuring Central NTP Time Synchronization and Legacy System Services in SIMATIC PCS 7 V8.1

To configure central time synchronization on a SIMATIC PCS 7 V8.1 system, establish a unified Network Time Protocol (NTP) hierarchy operating over UDP port 123 in UTC time. Designate an external GPS/radio master clock (such as SICLOCK) or configure the primary OS Server as the local NTP time master using the Windows Time service (w32time). In HW Config, configure the CP 443-1 communications processor to synchronize via NTP and forward time to the S7-400 CPU (set as time slave on the MPI/internal bus). On non-WinCC stations—including Process Historian, Information Server, Domain Controllers, and engineering clients—configure the Windows Time service to synchronize directly against the primary NTP master. For systems running discontinued PCS 7 versions (< V8.2), technical documentation, hotfixes, and security patches require an active Siemens Legacy System Services (LSS) contract.

Table of Contents

Executive Summary

In distributed process control systems, millisecond-accurate time synchronization is essential for sequence-of-events (SOE) recording, deterministic alarm ordering, and historical process data archiving. In a PCS 7 V8.1 architecture, the plant network encompasses not only S7-400 automation controllers and WinCC operator stations, but also auxiliary computers without WinCC Runtime: Process Historian servers, SIMATIC Information Server reporting engines, domain controllers, and office clients.

Engineers maintaining PCS 7 V8.1 systems frequently struggle to implement uniform time synchronization across this heterogeneous infrastructure, particularly in small plants lacking dedicated hardware GPS clocks. Furthermore, because PCS 7 V8.1 is officially discontinued and past mainstream support, accessing official manuals and downloads on the Siemens Industry Online Support (SIOS) portal requires understanding the Siemens Legacy System Services (LSS) framework. This technical guide outlines the architecture of NTP time distribution, provides the step-by-step procedure to configure Windows operating systems and S7-400 hardware as synchronized NTP clients, explains how to verify time synchronization via automated scripts, and defines the commercial terms of Legacy System Services.

Architecture and Fundamental Mechanics

Time synchronization in SIMATIC PCS 7 V8.1 spans two distinct operational tiers using the Network Time Protocol (NTP, RFC 2030):
1. The NTP Time Master Hierarchy:
* Stratum 1 Master: A high-precision hardware time transmitter (such as Siemens SICLOCK TC 100/TC 400 or GPS master clock).
* Stratum 2 Server (Software Master): In small-to-medium installations lacking a GPS receiver, the primary OS Server (OS_SRV01) acts as the local NTP server for the facility, disciplined by local quartz oscillator or external internet NTP pools.
* All controllers, redundant servers, historians, and clients act as NTP clients synchronized to this master reference.
2. Automation System (AS) Synchronization Architecture:
* S7-400 controllers do not connect directly to Windows time services. Instead, the Industrial Ethernet communications processor (CP 443-1) runs an onboard NTP client over the Plant Bus.
* The CP 443-1 receives NTP packets on UDP port 123, adjusts its internal clock, and forwards the time frame across the S7-400 backplane bus to the CPU.
* The S7-400 CPU properties (Diagnostics/Clock tab) must be configured as As slave on the MPI/internal bus.
* All controller clocks must operate strictly in Coordinated Universal Time (UTC) without daylight saving adjustments.
3. Non-WinCC Station Synchronization via Windows Time Service (w32time):
* Auxiliary servers (Process Historian, Information Server) synchronize using the native Windows Time service configured via command-line utility w32tm.
4. Commercial Framework: Legacy System Services (LSS):
* Siemens designates PCS 7 releases older than V8.2 as legacy products.
* Access to software patches, restricted technical articles, security updates, and hotline technical support for PCS 7 V8.1 requires an active Siemens Legacy System Services (LSS) service agreement (Entry ID: 4802).

Step-by-Step Implementation Procedure

Step 1: Configure Primary OS Server as NTP Master

  1. Log onto the primary OS Server (OS_SRV01) with administrative privileges.
  2. Open an elevated Windows Command Prompt (Run as administrator).
  3. Configure the Windows Time service to announce itself as a reliable NTP server:
    cmd reg add HKLM\SYSTEM\CurrentControlSet\Services\W32Time\Config /v LocalClockDispersion /t REG_DWORD /d 0 /f reg add HKLM\SYSTEM\CurrentControlSet\Services\W32Time\Parameters /v Type /t REG_SZ /d NTP /f reg add HKLM\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpServer /v Enabled /t REG_DWORD /d 1 /f net stop w32time && net start w32time w32tm /config /reliable:yes /update

Step 2: Configure S7-400 CPU and CP 443-1 in HW Config

  1. In SIMATIC Manager, open HW Config for the S7-400 / S7-400H station.
  2. Double-click the CP 443-1 module to open its Object Properties.
  3. On the Time-of-Day Synchronization tab:
    * Check the box: Enable NTP time-of-day synchronization.
    * Enter the IP address of the primary NTP server (OS_SRV01: e.g., 192.168.1.11).
    * Enter the IP address of the backup NTP server (OS_SRV02: e.g., 192.168.1.12).
    * Set the update interval to 10 seconds.
    * Check the box: Forward time-of-day synchronization to CPU.
  4. Double-click the S7-400 CPU to open its Object Properties.
  5. On the Diagnostics/Clock tab, verify synchronization is set to As slave on the MPI/internal bus.
  6. Save, compile, and download HW Config to the controller.

Step 3: Configure WinCC Time Synchronization Editor on OS Stations

  1. Open WinCC Explorer on the OS Servers and Clients.
  2. In the navigation tree, open the Time Synchronization editor.
  3. In the dialog, select Use NTP or check Slave on Terminal Bus.
  4. Ensure UTC (Coordinated Universal Time) is selected globally.
  5. Save settings and close the editor.

Step 4: Configure Non-WinCC Stations (Process Historian, Information Server)

  1. On each auxiliary station, open Windows Command Prompt as Administrator.
  2. Point the Windows Time client to the primary and secondary OS servers:
    cmd w32tm /config /manualpeerlist:"192.168.2.11,0x8 192.168.2.12,0x8" /syncfromflags:manual /update net stop w32time && net start w32time w32tm /resync /force

Step 5: Automate Verification with a Batch Diagnostic Script

  1. Create a diagnostic script named CheckTimeSync.bat on the Engineering Station:
    cmd @echo off echo ================================================== echo SIMATIC PCS 7 Terminal Bus Time Sync Status echo ================================================== w32tm /query /status echo. echo Source Peer: w32tm /query /peers pause
  2. Execute the batch script across workstations to confirm sub-millisecond offset from the master clock.

Verification

  1. In Windows Command Prompt on any OS client, run: w32tm /query /status.
  2. Confirm that the 'Source' reports the IP address of the designated NTP server and 'Leap Indicator' shows 0 (no warning).
  3. In SIMATIC Manager, select the S7-400 CPU and open PLC > Module Information > Time System tab.
  4. Confirm that the CPU status reports 'Synchronized' and that the system clock matches UTC time.
  5. In WinCC Runtime, inspect the overview header clock and confirm that no horizontal strikethrough lines appear across the time digits.
  6. Generate an alarm in WinCC and verify that the timestamp matches the exact millisecond recorded in the AS diagnostic buffer.

Limitations and Operational Precautions

  1. Never combine SIMATIC Mode (Layer 2 MAC broadcast) and NTP Mode on the same physical plant bus; mixing protocols causes competing time telegrams and severe clock jitter.
  2. PCS 7 V8.1 is discontinued; software updates, security hotfixes, and extended support require an active Siemens Legacy System Services (LSS) contract.
  3. High-traffic industrial Ethernet switches must not block or throttle UDP port 123 packets.
  4. Changing system time backwards while batch recipes or archive logging are active can corrupt database sequences; perform time reconfigurations during planned outages.

Engineer FAQ

Why must all PCS 7 controllers use UTC instead of local time?

Operating in UTC prevents clock discontinuities and duplicate timestamps during Daylight Saving Time (DST) seasonal transitions. WinCC faceplates automatically convert UTC to local time for operator display.

What is the Siemens Legacy System Services (LSS) contract?

LSS is a commercial service agreement providing technical support, software hotfixes, and access to archived documentation for discontinued PCS 7 versions older than V8.2 (Entry ID: 4802).

Can I synchronize Process Historian without WinCC Time Synchronization?

Yes. Non-WinCC computers synchronize directly using the standard Windows Time service (w32time) configured to query the central NTP master clock.

What network port does NTP use in PCS 7?

NTP communicates via standard UDP port 123.

Where can I find licensing and support terms for Legacy System Services?

Consult an authorized Siemens distributor or the Siemens Industry Mall to evaluate Legacy System Services contracts and modernization upgrade pathways.

Technical References

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Related Tags

  • Time Synchronization
  • NTP
  • PCS 7 V8.1
  • CP 443-1
  • Legacy System Services
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