PLC PC Data Exchange: Without OPC Server?

When it comes to the data exchange between the PC world and the automation world, there is no way around an OPC server, right? The remaining question is: Use OPC UA, or not? What are the alternatives? Learn more in this article.

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Faster data exchange without OPC UA

Especially relevant for S7 1200 CPUs

Some advantages of a direct ProfiNet (RFC1006) connection are obvious:

Not quite as obvious, however, is the speed advantage of a direct connection without OPC UA, especially compared to the now outdated OPC DA. We have performed a series of measurements with an S7 1212 CPU and determined how fast a direct data connection from a PC to the S7 can be:

The diagram shows how fast it can be. We measured the speed with a S7-1200 CPU with data sets of different sizes. The data records are read from a data block and written to an Excel file. The times here are well below 200ms per data set. It should be noted that a large part of the time is required for writing to the Excel file. Pure data transfer via Ethernet is much faster.

How fast is the data transfer in your S7 project?

It depends on these factors

The transmission time or the speed depends on many factors: PLC CPU, program workload, network, PC speed, etc. With a fast S7-1500 CPU and almost ideal conditions we could realize transfer times in the range of 1 ms. The S7-1200 used here for the measurement is of course slower. There the pure transmission times are about 10 to 12 ms.

You notice: It is not trivial to answer this question. We will be happy to advise you free of charge and without obligation and answer specific questions about your project and your plans.

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Profinet and OPC UA in comparison

Comparing a direct S7 connection (RFC 1006) and OPC UA

A lot has happened in the meantime with the new OPC UA standard. Many problems of the old OPC DA have been solved. So it is still a small effort to install an OPC UA server on a Siemens S7 PLC, but it is much easier than in former OPC DA days.

A big advantage of OPC UA compared to a direct S7 connection is the security. With OPC UA you can easily establish encrypted data connections to Siemens S7 PLCs. This can be done by user name and password, and also with a certificate.

S7 direkt

OPC UA

One solution for Profinet and OPC UA

No matter whether you decide for a direct S7 connection (Profinet) or for OPC UA: With our DataSuite software you are well positioned. After you have connected the PLC to the PC, you will hardly notice the difference between OPC UA and a direct S7 connection via RPC 1006.

PC connection via OPC has never been easier. The DataSuite software acts as OPC UA client for Windows and provides you with OPC data from the connected S7 controllers as documents. These can be PDFs, Excel files or HTML files. Alternatively, an export and import with SQL databases is possible.

Conclusion

The days of OPC DA are over. If you want to focus on security and future viability in machine connectivity today, there is no getting around OPC UA. Alternatively, there is the possibility to save costs with an S7 direct connection to still ensure a good data exchange.

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