Establishing Communication with a SIMATIC STEP 7 PLC via Profibus DP

This article provides step-by-step instructions for establishing communication with a Siemens SIMATIC STEP 7 PLC using Profibus DP.

The Q.bloxx Classic and Q.series X modules can be supplied with specialized firmware to facilitate direct communication with the modules via Profibus DP. For further information on initiating communication with the Profibus DP modules, please refer to this article.

The steps below describe how to set up communication with the Profibus DP modules using SIMATIC Manager.

  1. In SIMATIC Manager, initiate a new project and incorporate a SIMATIC 300 Station.siemens1-1

  2. Navigate to the hardware configuration section in SIMATIC Manager.

  3. Double-click on the Hardware element in SIMATIC Manager to open the hardware configuration. Next, go to the Options menu and select Install GSD File... Ensure that both the "Slots and Components" and "Catalog" window are closed. After installing the GSD file, refresh the catalog.
    siemens3đŸ‘‰ The GSD files for modules are typically located in the ICP 100 program directory (C:\Users\Public\Documents\Gantner Instruments\ICP100\GSD), or they can be downloaded from the Gantner Instruments website:

  4. Upon installing the GSD files, the hardware configuration process must be initiated. Begin by attaching the PLC components to their respective slots with the correct type identifications. Drag and drop the profile rail from the right window into the upper left window to insert the profile rail element, which will then appear.siemens4

  5. Drag and drop a Power Supply (PS) from the right window to the first channel of the profile rail element to add it.siemens5

  6. Drag and drop a PLC controller from the right window to the second channel of the profile rail element. This action will prompt the configuration window for the communication parameters of the DP master (PLC) to open. Clicking on the New button will lead you further to the bus configurations.siemens6

  7. Navigate to the Network Settings tab to configure the general DP settings and the transmission rate. Click on the Bus parameters… button to access a new window for configuring the DP timing data settings. Do not activate the parameter "Turn on cyclic distribution of the bus parameters", as this is not supported by the modules.  siemens7

  8. Drag and drop a Profibus DP module from the right window to the PROFIBUS-line in the left window to connect the slave to the bus line. Ensure to set the correct address of the module, noting that the address can be adjusted later if needed.


  9. Slave setup can be accomplished through drag and drop functionality. In the right window, the required input and output data bytes are listed, which must be filled into the lower-left window based on the current slave configuration. siemens10

  10. To set up the channels in Simatic, you must be familiar with the Profibus representation for each channel. This information can be obtained from the ICP 100 configuration. siemens11

  11. Once all slaves are configured in the SIMATIC software as outlined above, navigate to the Station menu in Simatic and select Save and Compile.

  12. Switch to SIMATIC Manager, select Blocks, and load the project.siemens13

  13. When duplicating an OP1 (organization block 1) at the block layer, additional OBs required for PLC communication with Profibus DP will be generated. Create OB80, OB81, OB82, OB85, OB86, OB87, OB121, and OB122. Detailed descriptions of organization blocks OB86 and OB122 can be found in Siemens Help.siemens14

  14. By clicking the Download button, the entire SIMATIC project will be transferred to the PLC.