PC-PLC Communication
for Industry 4.0 and IIoT

In Industry 4.0 and IIoT, the demands on the exchange of data are becoming higher and higher. The right solution should therefore not only be secure, but also high-performance and flexible. One of the simplest options is to rely on an already defined interface, which many devices and products offer as standard. The advantage here is that data can be exchanged without much effort or additional adjustments.

Use cases for a Communications Library

However, there are also use cases where the use of OPC UA is not possible. This may be because the corresponding interface is not offered or because the defined functional scope of the OPC UA protocol is not sufficient. For such cases, too, there is a solution - the use of a communication library with which you can process the data completely individually adapted to your situation and also enjoy an even greater range of functions.

OPC Server or Communication Library: The options at a glance

Depending on your use case, you have various options here. The most widely used is the new industry standard OPC UA. This communication protocol is already offered by many software products as an interface option. It is based on TCP/IP via ethernet or alternatively on a SOAP communication. The great advantage of this standardized interface is that data can be easily exchanged between products from different manufacturers. No programming knowledge is required for the implementation.
However, if you need more functionality than is offered by the OPC standard, it is a good idea to implement this with a communication library. This allows you to realize a wide range of functionality according to your requirements. The integration of data from the PLC into your own software is thus no problem.

Option 1: OPC UA - The new Industry Standard

OPC UA works according to the simple client/server principle. Clients are usually the programs that read and write or process data.
In order to be able to exchange this data between different programs or to use it for your own specific use case, you need a server which manages the communication.
Your advantages when using OPC UA are:
  • Is already offered as an interface by many software products
  • Usage without programming knowledge
  • Industrial standard
  • Client/Server principle

Alternative: Older Standard OPC DA

If your software does not support OPC UA, but instead the older standard OPC DA, also called OPC Classic, you can alternatively use an OPC DA server for communication. With this variant you also have the possibility to address older software products via an OPC interface and thus better integrate them into your IT infrastructure.
In contrast to the object-oriented OPC UA standard, however, OPC DA communication is based on DCOM. Since the latest update of the DCOM protocol, though, network-based communication is only possible via packet-based authentication.
If, on the other hand, you have the choice between OPC DA and OPC UA, we always recommend using the newer and more secure standard OPC UA.

Option 2: Using a Communication Library

A standard interface is often not sufficient for creating company-specific programs. If this is the case, the use of a communication library is recommended. This usually has a significantly larger range of functions and can be used quite flexibly.
For example, reading and writing data from the controller depending on certain events should not be a problem. Prerequisite for the use of a library are programming skills, but you need them anyway to create your own software.
Therefore, rely on a communication library when
  • the functional scope of standard interfaces such as OPC is not sufficient
  • you would like to integrate specific functionalities into your own software

The comparison: Which option should I choose?

Depending on your situation, either one or the other may be a better fit. Especially if the exchange is to take place between many devices and programs from a wide range of manufacturers that already offer the standard OPC UA interface, the use of an OPC UA server is a good choice. If you are concerned with the use of a large number of options or your requirements cannot be implemented with such an interface, then using a communication library is the better decision. To help you decide, below is a brief overview.


  • easy data exchange between different manufacturers
  • standardized interface
  • industry standard already offered by many software products
  • no programming knowledge necessary
  • range of functions provided by the standard
  • client/server principle


  • the probably best performing OPC UA server on the market
  • certified by the OPC Foundation
  • for communication with S7 and SINUMERIK controllers
  • supports Secure Communication

Communication Library

  • freely createable programs
  • process data completely individualized
  • best customization possibilities for every application
  • offers functionalities that go beyond the OPC protocol
  • programming knowledge necessary


  • extensive and proven library
  • for different operating systems, communication channels, programming languages
  • for S5, S7, SINUMERIK, LOGO!
  • supports Secure Communication and symbolic access
  • maintenance contract available

Standard interface OPC UA or Communication Library?

With the presented solutions from DELTA LOGIC, you are right in the middle of the digitalization of your plant, regardless of whether you work with Siemens PLCs or use SINUMERIK controllers.

You are also well equipped for the future when working with machine tool controllers with our products. In addition to the SINUMERIK ONE, the 840D sl, 840D pl and 810D pl controllers, they also support work with the Digital Twin of the SINUMERIK ONE - Create MyVirtual Machine.

You are not yet sure which product you should use exactly for your use case? The possibilities offered by Industry 4.0 and IIot mean that the exchange of data and information between the production-related process control of your Operational Technology (OT) and data-processing Information Technology (IT) is becoming increasingly important. Would you like more information about the possibilities that DELTA LOGIC products offer you when it comes to connecting your OT to your IT?

Then take a look at our YouTube channel or write to us directly via our contact form and we will get back to you. We would also be happy to advise you on our other products for PC-PLC communication.

OPC UA - High Performance for Industry 4.0 and IIoT
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ACCON OPC UA Server High-performance, certified OPC UA server for S7 and SINUMERIK

For access to your Siemens controller via OPC UA the ACCON OPC UA Server is the right choice. Besides S7 PLCs, it is also suitable for SINUMERIK machine tool controllers. One of the few servers certified by the OPC Foundation that also supports optimized data blocks.

From €790.00*
ACCON AGLink The fast and flexible communication library for smooth PC-PLC data exchange

ACCON AGLink enables the data exchange between PC and Siemens controller. Among other things, it offers functions for data access, diagnostics and time synchronization. Compatible with various operating systems, programming languages and controllers, such as S7, S5, SINUMERIK, LOGO! and Siemens-compatible PLCs.