APA offered to replace the controller with the new model, S7-1518F-4PN/DP, as well as to optimise the source code.

In the first step of the replacement procedure, the program had to undergo migration from S7-400 to S7-1500 controller. For this, the “Migrate project” function from the Siemens TIA Portal 15.1 software was used. This means that the group working principle remained constant. The system architecture of the controllers S7-1500 and S7-400 differ significantly. For S7-400, the basic programming language is STL, and all operations are performed using system registers. This causes blocks written in LAD to be a graphical representation of an STL code. In contrast to the S7-400 controllers, the new Simatic controllers are free of programming language limitations; the program is not translated to STL, but to a code that can be read only by the controllers. The system registers concept has been abandoned. In the second step, a hardware configuration was prepared in HW. Two additional Phoenix Contact proxy modules were added for communication with the Profinet network – Interbus. In the third step, additional program modifications resulting from the new architecture of the S7-1500 controllers were introduced.

• FTP communication function,
• TCP/IP communication function,
• Blocks (to enable their handling by the S7-1500 controller),
• References to DB data blocks,
• References to variables.

Benefits

The needs of the client were fully satisfied, and the project goals were reached. The main goal of the project was the reduction of the controller cycle time. We managed to do this in a spectacular way: replacing the controller and optimising the code allowed us to reduce the controller cycle time to an impressive 27 ms.

Interesting fact

Before the changes, the cycle time was approx. 150 ms; simple maths will tell us that the operations are now performed almost 5x faster.