C135 PCS 7 (PCS7)
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Configuring 1 ms High-Precision Time Stamping with ET 200SP HA and DTS 4138S

Configuring 1 ms High-Precision Time Stamping with ET 200SP HA and DTS 4138S

To implement plant-wide 1 ms high-precision time stamping (Sequence of Events / SOE) in SIMATIC PCS 7 with redundant CPU 410-5H controllers and ET 200SP HA on PROFINET using the approved Bürk Mobatime DTS 4138S master clock, connect LAN1 of the DTS 4138S to the plant bus switch network (TIME-NET) and LAN2 to the Terminal Bus. Although legacy manuals showed three physical clock ports, SIOS FAQ 109750520 confirms that LAN1 distributes high-precision time to both H-CPUs and ET 200SP HA interface modules via industrial Ethernet switches, while LAN2 synchronizes OS Servers, OS Clients, and Engineering Stations via standard NTP. All hardware must be validated via an authorized Siemens distributor or the Siemens Industry Mall.

Table of Contents

Executive Summary

In power generation, chemical synthesis, and oil & gas refining automated with SIMATIC PCS 7, post-trip fault analysis mandates high-precision time stamping (1 ms resolution) for digital events across thousands of field inputs. Following the discontinuation of the legacy SICLOCK TC400 central system clock, Siemens officially certified the Bürk Mobatime DTS 4138S master clock for PCS 7 systems running CPU 410-5H and ET 200SP HA distributed I/O. Commissioning engineers frequently encounter confusion when reviewing the reference manual 'PCS 7 High-Precision Time Stamping with ET 200SP HA' (Entry ID: 109747238), which illustrates three independent clock outputs, whereas the physical DTS 4138S features only two Gigabit LAN ports. Resolving this discrepancy requires deploying a converged industrial switch architecture connecting LAN1 to the Plant Bus / TIME-NET and LAN2 to the Terminal Bus.

Architecture and Fundamental Mechanics

The architecture of 1 ms high-precision time stamping over PROFINET combines hardware-level timestamping with multi-tier network synchronization:

1. Hardware Timestamping at the ET 200SP HA Module Level

In classical systems, time stamping occurred at the CPU scan rate (10-100 ms). In the ET 200SP HA system:
- Digital input modules (e.g., DI 16x24VDC HA, DI 32x24VDC HA) evaluate edge transitions directly in hardware ASIC chips.
- When a contact trips, the input module assigns a 1 ms resolution timestamp immediately at the physical terminal.
- The timestamped event is buffered in the module and transmitted via PROFINET system redundancy (S2/R1) to the CPU 410-5H, which forwards the alarm to the WinCC OS Alarm Logging buffer without jitter.

2. The Bürk Mobatime DTS 4138S Dual-Port Topology

The DTS 4138S receives ultra-precise GPS or DCF77 radio time and provides two isolated Gigabit Ethernet interfaces:
- LAN 1 (Plant Bus / TIME-NET): Configured with high-accuracy NTP/PTP or SIMATIC time-of-day protocols. It connects to the managed SCALANCE switch infrastructure of the plant bus. Both redundant CPU 410-5H controllers and the ET 200SP HA IM 155-6 PN HA interface modules receive time synchronization frames through the switch network from LAN 1.
- LAN 2 (Terminal Bus): Connects to the plant terminal bus network, broadcasting standard NTP time to OS Servers, OS Clients, Process Historian, and Engineering Stations.
- This dual-port topology completely eliminates the perceived need for a third physical clock port, ensuring full system-wide synchronization while maintaining strict physical network segregation.

Step-by-Step Implementation Procedure

To engineer 1 ms time stamping with CPU 410-5H, ET 200SP HA, and DTS 4138S:

Step 1: Configure the Bürk Mobatime DTS 4138S Master Clock

  1. Access the web management interface of the DTS 4138S.
  2. Ensure GPS antenna synchronization is locked (satellite fix established).
  3. Configure LAN 1:
    - IP Address: assign an IP within the Plant Bus / PROFINET subnet (e.g., 192.168.0.250).
    - Enable NTP Server mode.
  4. Configure LAN 2:
    - IP Address: assign an IP within the Terminal Bus subnet (e.g., 192.168.1.250).
    - Enable NTP Server mode.

Step 2: Configure CPU 410-5H and Plant Bus in HW Config

  1. In SIMATIC Manager, open HW Config for the redundant CPU 410-5H station.
  2. Open the properties of the PROFINET / Industrial Ethernet interface.
  3. Under Time-of-Day Synchronization:
    - Check Enable NTP mode.
    - Add the IP address of DTS 4138S LAN 1 (192.168.0.250).
    - Set synchronization interval to 10 seconds.
  4. Under CPU Properties -> Diagnostics/Clock:
    - Set Synchronization mode to As slave.

Step 3: Configure High-Precision Time Stamping on ET 200SP HA Modules

  1. In HW Config, select the ET 200SP HA station.
  2. Open the properties of the digital input module (e.g., DI 16x24VDC HA).
  3. Under module parameters, check High-precision time stamping (1 ms).
  4. Configure edge evaluation ($0
    ightarrow 1$ and/or $1
    ightarrow 0$) for critical trip channels.
  5. Save and compile HW Config; download to the redundant CPU 410-5H.

Step 4: Configure Terminal Bus Time Synchronization

  1. In WinCC Explorer on each OS Server and Client, open the Time Synchronization editor.
  2. Select Synchronization via terminal bus.
  3. Configure the station to take time via NTP from the DTS 4138S LAN 2 IP address (192.168.1.250).
  4. Save settings and restart WinCC Runtime.

Verification

To confirm 1 ms time stamping operation:

  1. Module Diagnostics Inspection:
    - In HW Config online mode, double-click the ET 200SP HA DI module.
    - Verify that the module diagnostic status indicates 'Time stamping synchronized' with zero synchronization loss errors.

  2. Trip Chronology Test:
    - Simultaneously trip two digital inputs across different ET 200SP HA racks using a test switch.
    - Open the WinCC Alarm Logging sequence-of-events list.
    - Verify that both alarms display millisecond timestamps reflecting their true physical trigger order with 1 ms resolution.

Limitations and Operational Precautions

Operational limitations and precautions:

  1. Switch Quality of Service (QoS): Plant bus SCALANCE switches must prioritize time synchronization packets (IEEE 1588 / NTP) over standard acyclic data to avoid queuing latency.
  2. Quantity Framework Ceilings: Siemens specifies a maximum limit of time-stamped digital channels per CPU 410-5H (typically up to 4000 channels) to ensure communication buffers are not overrun during trip avalanches.
  3. Firmware Prerequisites: High-precision time stamping with ET 200SP HA requires CPU 410-5H firmware V8.2 or higher and PCS 7 V9.0 or higher.
  4. Commercial Disclaimer: Verify all hardware components, master clocks, and software licensing packages with an authorized Siemens distributor or the Siemens Industry Mall.

Engineer FAQ

Why does the DTS 4138S have only two ports if the manual showed three?

Siemens SIOS FAQ 109750520 clarifies that LAN1 connects to the Plant Bus switch network (synchronizing both H-CPUs and ET 200SP HA stations via switch distribution), while LAN2 synchronizes the Terminal Bus.

Which master clock replaced the discontinued SICLOCK TC400?

The Bürk Mobatime DTS 4138S (and DTS 4128) is the officially approved and released central plant master clock for SIMATIC PCS 7.

Where does the 1 ms timestamp originate in the ET 200SP HA system?

The timestamp is generated directly inside the digital input module ASIC hardware at the physical terminal, eliminating CPU scan-time jitter.

What protocol synchronizes the CPU 410-5H with the DTS 4138S?

Network Time Protocol (NTP) over Industrial Ethernet.

Can time-stamped events be visualized in WinCC Alarm Logging?

Yes. WinCC Alarm Logging natively displays high-precision timestamps down to millisecond resolution in chronological sequence.

Technical References

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Related Tags

  • High-Precision Time Stamping
  • DTS 4138S
  • ET 200SP HA
  • Sequence of Events
  • NTP Synchronization
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