Joining two worlds

Illustration | Bosch Rexroth AG
Marginal Column

Rexroth uses Open Core Engineering to link the PLC and IT worlds and gives users new freedoms and options for customization. One special interface acts as the bridge between all the platforms: the Open Core Interface. Norbert Sasse, Sales Product Management Motion Logic Systems, and Thomas Gabler, Engineering Automation Systems Firmware, explain the course of development and what advantages the user can expect.


Ongoing developments in automation technology are continuously changing the face of mechanical engineering. To an ever increasing extent, the intelligence built into a machine’s software is decisive to market success. Machine manufacturers’ competitive positions and survivability will also be measured on the basis of how quickly they can implement these innovative software functions and integrate new IT technologies. It is against this background that the requirements for control software rise. Such programs are to solve complex automation tasks, integrate a variety of drive technologies, and network components at the production level. Engineering environments have to contribute to ensuring that these can be implemented efficiently and with the required degree of flexibility. Only in this way are mechanical engineering companies able to bring creative ideas to fruition.

Direct access to the controls

Our response to these demands is Open Core Engineering; it bridges the gap between machine automation and the IT world. For the first time ever, it gives every user direct functional access to the core of the controls. With the Open Core Interface, Open Core Engineering now makes it possible for high-level language programmers to access PLC controls directly and realize individualized applications. All the customers need is the Software Development Kit for their preferred platform.

The impetus for completely opening the control core was received both from in-house and outside sources. Customers approached us again and again when they wanted to integrate sophisticated HLL controls into new hardware. Without access to the control core, they could not do this on their own. In addition, we discovered on our own that control firmware was becoming ever more complex, making it desirable to use automated test routines.

The development of an interface was to let us test firmware functions on our desktop PCs. In this way we were at the same starting point as a customer who, working on his preferred platform – a PC, for instance – wanted to access Rexroth controls. We developed an interface that lets him use a variety of high-level languages to access the control. The cornerstone for the Open Core Interface was laid.

New freedom in adaptations

Illustration | Bosch Rexroth AG

Example of a motion control app running on the Google Android operating system.


Dynamic developments in the field of smartphones and tablet computers encouraged us to link widespread development environments – such as Eclipse for Google Android and xCode for Apple iOS – to our interface. In that way, a series of toolboxes was gradually created for today’s most popular development environments for IT automation. Modifying the interface to match the various environments was relatively easy. It proved more difficult to program properly functioning and optically appealing application examples on the corresponding terminal equipment, since this was new territory for us.

The Open Core Interface we shepherded from internal development to the market shows that it was worth all the effort. This gives users the freedom to adapt controls precisely to their needs – working on the platform they are used to. This new interface lends efficiency to customers running simulations, controlling automated processes, and reading out diagnostics data. The technical implementation of the Open Core Interface used object-oriented software techniques and is written so that it can readily be integrated into any desired system. Solving this demanding programming task was done superbly by firmware developers Sebastian Krauskopf and Jens Reckwell.

Moving smartly into the future

Illustration | Bosch Rexroth AG

Example of a diagnosis app running on Google Android.


By linking a number of popular platforms to machine controls via the Open Core Interface, we are keeping pace with the dynamics of software development. In the same way, we will be able to accommodate future developments. What’s more, we profit from the input of a significantly larger number of developers, with many new ideas. We are banking, in part, on collective intelligence. The threshold for familiarization with the Open Core Interface is extremely low. We have found that – after just two hours – experienced HLL programmers are able to make a connection to the machine and utilize the access to the control core.

The possibilities here are just about unlimited. From simple Excel worksheets to highly complex programs, many applications can be linked to the control core using the Open Core Interface. Quite promising are the so-called smart apps. These show off the interface’s potential especially impressively. Using the multi-touch control, the accelerometer that senses orientation, and the GPS function built into smart devices makes possible especially intuitive and simple operation. With Apple iOS and Google Android, the interface supports today’s most important operating systems for smart devices.

Thus machine manufacturers can make up native apps that run entirely autonomously on the target unit – a tablet computer, for instance, and place only a minimum load on the control system. Examples of such programs are diagnostics apps that display only relevant measured values, filtered according to the user's location on the shop floor or personal access authorization. Further opportunities for use will be found in the field of rapid control prototyping, i.e. simulating machine processes in the early stages of the engineering process. Another is programming real-time functions which can be run right on the control software. There are virtually no technical limits on the mechanical engineer’s creativity when writing other applications.


Photo | Bosch Rexroth AG

Norbert Sasse,

Sales Product Management Motion Logic Systems,

Lohr, Germany

Photo | Bosch Rexroth AG

Thomas Gabler,

Engineering Automation Systems Firmware,

Lohr, Germany