Why Is Clock Synchronization Between PLC and HMI Necessary? How to Set Up Clock Synchronization?

To ensure that components such as the HMI operator interface and SIMATIC controllers operate with synchronized time, one of the following components must be used as the time master for all other components.

The component serving as the time master is referred to as the time master station.

The components that receive the time are known as time slave stations.


Time Synchronization: Its Crucial Role in Various Applications

Time synchronization is of utmost importance, particularly in the following application areas:

  • Data Logging and Storage
  • Alarm Systems
  • Protocol Conversion
  • Energy Data Management

To provide a better overview, this application example is divided into three parts:

Guidance Documentation aims to provide a brief summary and explain specific terminology, making it easier to locate existing FAQs.

First Example Project demonstrates "Clock Synchronization between HMI Operator Interface and SIMATIC PLC."

Second Example Project shows "Clock Synchronization between WinCC Runtime Professional and SIMATIC PLC."


Clock Synchronization between HMI Operator Interface and SIMATIC PLC

The example project illustrates various possibilities for clock synchronization and their programming implementations.

Distinctions exist among the following synchronization types:

  • HMI Clock Synchronization (Master)
  • HMI Clock Synchronization (Slave)
  • Area Pointer: Date/Time
  • Area Pointer: Date/Time PLC
  • Area Pointer: Control Commands 14 and 15

The example project addresses two tasks:

For the first task, the HMI user interface serves as the timing component.
(HMI Operating Unit → SIMATIC Controller)

In the second task, the SIMATIC controller acts as the timing component.
(SIMATIC Controller → HMI Operator Interface)

Example projects are stored for each synchronization type.

This description applies to the following SIMATIC controllers and HMI operator interfaces:

SIMATIC Controllers

  • SIMATIC S7-1200
  • SIMATIC S7-1500
  • SIMATIC S7-300
  • SIMATIC S7-400

HMI Operating Devices

  • SIMATIC Basic Panels
  • SIMATIC Panels
  • SIMATIC Comfort Panels
  • SIMATIC Multi-Panels
  • SIMATIC Mobile Panels
  • SIMATIC RT Advanced

Clock Synchronization between WinCC Runtime Professional and SIMATIC PLC

The clock time of a high-level industrial PC (time master) is transmitted to all connected devices (time slaves).

The example project includes two tasks, depending on the hardware used:

  • Adjusting time and date via interface variables.
  • Comparing time and date using the NTP protocol.

This description applies to the following SIMATIC controllers and HMI operator interfaces:

SIMATIC Controllers

  • SIMATIC S7-1200
  • SIMATIC S7-1500
  • SIMATIC S7-300
  • SIMATIC S7-400

Time Master

  • PC with WinCC Runtime Professional
  • IPC when using the NTP protocol