Siemens Industry Online Support
Siemens AG
Entry type: Application example Entry ID: 39040038, Entry date: 07/25/2014

Data synchronization over open communication between multiple field devices (S7-1200) and a head PLC (S7-1200/ S7-300/ WinAC) (Set 17).

  • Entry
  • Associated product(s)
The application example demonstrates with a concrete example the data synchronization between one head PLC and several field PLCs.

For synchronization tasks and the exchange of control and status information between one head PLC and several field PLCs, a performant cyclic communication is needed.
The following points must be noted here:

  • Supply of all the field PLCs with the same or different sets of data from the head PLC (down sync).
  • Updating the sets of data from all the field PLCs in the head PLC (up sync).

For solving the task, the block DATASYNC_X has been developed, which automatically assumes the control of the data synchronization:

  • Function block DATASYNC_HEAD for the head PLC
  • Function block DATASYNC_SUB for the field PLC

The application example is demonstrated with a concrete example - the control of solar trackers. The expression solar tracker means solar energy systems which can be tracked according to the position of the sun to ensure the best possible energy yields.
For the field PLC, a CPU S7-1200 is used in this example. For the head PLC, this solution uses two types of devices:

  • An S7-1200 controller
  • An S7-300/400/ IPC with WinAC
The head PLC sequentially establishes an ISO-on-TCP communication connection with each field PLC and terminates it again. Data is sent to the field PLCs and data is received from them. After all field PLCs have been operated, the process is repeated.
The data communication among the PLCs is displayed in images by the HMI panel.

The realization of the data synchronisation with the DATASYNC_X function block has the following advantages for you:

  • simple and transparent integration of the DATASYNC_X blocks in your existing user program.
  • flexible modification of the quantity structure for the send and receive of the data.
  • number of field PLCs is variabel.

  Documentation (1,3 MB) 
 Registrierung notwendig  Project (TIA Portal V13 SP1) (16,2 MB) 

Last Changes
Security Notice actualized, update Project to V13 SP1

Additional Keywords
S7-1200, data synchronization, data concentrator

Security information
In order to protect technical infrastructures, systems, machines and networks against cyber threats, it is necessary to implement – and continuously maintain – a holistic, state-of-the-art IT security concept. Siemens’ products and solutions constitute one element of such a concept. For more information about cyber security, please visit
Support to the statistics
With this function the IDs found are listed according to number (format .txt).

Generate list
Copy URL
Display page in new design
mySupport Cockpit