If you want to know how many robots are working in production at Daimler, you have to go there and count them yourself. The reason: the robots cannot be found and counted in the network as they are generally not connected. Any inkjet printer from a discount store for 80 euros can do this, but most industrial components today cannot. There is enormous untapped innovation potential here!"

The Codesys Edge Gateway is the communication interface from the control plant to the Automation Server and provides the information for the digital image of all connected controllers.

© 3S-Smart Software Solutions

The next prerequisite: software interfaces for standardized access to the control systems. Many different manufacturers with Codesys-compatible systems use a special service for this, the so-called 'Codesys Gateway'. This is originally responsible for communication between the programming tool and the runtime on the device. It provides important functions, such as scanning the local network for compatible controllers or downloading applications.

This service typically runs on workstation PCs under Windows, but it can also be installed directly on the compatible devices as part of the runtime system. Appropriately equipped controllers thus become a router to other subsystems with Codesys runtime systems in the network. If the service is expanded to include common communication protocols for Industry 4.0 applications, it can provide information from connected controllers - for example, for the overview of devices in the company network mentioned at the beginning. In effect, the service implements edge computing, i.e. according to Wikipedia's definition, it moves "data and services away from central nodes [...] to the outer edges of a network" so that they are available for cloud-based systems. Suitably equipped devices thus become edge controllers, enabling the use of cloud technologies in industrial manufacturing.

The platform for Industry 4.0 administration

Once the information on the control landscape is available at the 'border' to the Internet, all that is needed is a suitable counterpart to administer the information and make it available for use - i.e. server software such as the upcoming 'Codesys Automation Server'. Installed on a private or public cloud server, this software provides an overview of all Codesys-compatible controllers in the network. To do this, the Edge Gateway first establishes the connection to the server, whereby the communication is encrypted and signed in every case. This means that certificates are required in pairs both on the server side and on the Edge device to enable mutual access.

Whether the edge service runs on a powerful PLC or a separate computer is irrelevant for the function. Once the connection is established, the Automation Server creates a so-called 'digital twin' for each device found, which represents the physical device: Are they modular PLCs, intelligent drives or panel controllers? Are all devices active without faults? Which applications and versions are they running? In addition, the Automation Server can read or write control data in order to parameterize the device or application for a very specific task or a special place of use.

For example, it could be that the same controller with an identical application is used several times in different system units: whether a printing unit of a sheet-fed offset press prints cyan or black is only determined by the filling of the color or by the IP address of the physical controller. Nevertheless, unit-specific parameters can be relevant - such as the ink moisture, which can differ from printing unit to printing unit. The same applies to many identical controllers in a commercial building: where these controllers are used - i.e. in which specific room or floor - or which additional tasks they are to perform for a room, can be defined by corresponding parameters. A commissioning engineer can set such parameters directly in the Codesys Automation Server for the task on site - completely without the IEC 61131-3 source code or the programming tool.

Added value through digital twins

How does a system operator benefit from a digital image of their control systems? No longer having to count them, but automatically receiving a complete overview is already an added value in itself. But that's not all! If the operator knows the status of all integrated devices, he can react to the failure of a control unit even if production does not stop in the event of a failure or no corresponding alarm message has been generated.

Overview of available Codesys Automation Server applications and their use in the field: Applications, devices and parameter sets can be conveniently managed via a web browser.

© 3S-Smart Software Solutions

If, for example, the control system for a mobile machine unit whose function is not used on a daily basis fails, the operator of the machinery can still see this immediately in the Automation Server. This is particularly valuable if the machine in question is in use somewhere in the field. The topology view provides a quick overview of not only the number but also the position of the respective devices in the network. This is because the Automation Server knows all the integrated controllers and - unlike conventional routers - provides really useful and meaningful information. This means that not only the IP address is displayed, but also, for example, the current software version for each device, the active application or the application parameter sets associated with the device.

In this way, the machine operator immediately recognizes which control unit should be brought up to date with a software update. Today, the motto "Never change a running system" is still often applied - even if an update could improve the functionality, performance or protection of the application. This is hardly surprising: maintenance personnel usually have to be directly on site at the machine for an update and physically connect the programming tool to the controller. The Automation Server also provides a remedy here: all control projects can be stored on the server as so-called boot applications - i.e. as executable files for the respective device platform.

This boot application then only needs to be transferred from the server to the target system for the mandatory update at some point. The added value is all the greater if an update - as in the case mentioned above - is to be rolled out to many similar devices at the same time. The update is then carried out from a central location to all selected controllers - if desired, also at night and automatically by script.

The steps for connecting devices

So what exactly needs to be done to be able to manage controllers via the Automation Server? First of all, a sufficiently powerful edge gateway is required that establishes the secure connection to the server via HTTPS or TLS. This can be a high-performance PLC with a Codesys runtime system in the network or a dedicated edge controller that performs encryption and signing via X.509 certificates. By downloading the project to the target controller, the device is then automatically registered in the server. In addition, each controller can be registered manually by entering a corresponding device ID or by scanning a barcode. A corresponding plug-in in the development system stores a PLC application directly on the Automation Server as a boot application. This can then be rolled out directly via the server's web interface, for example using a tablet or smartphone.

Furthermore, the user can configure various parameter sets for individual tasks, such as data exchange via OPC UA or visualization, in the symbol configuration of the development system in their project. With such a data set, they can also specify exactly which application variables are available as parameters in the server and should be read or written directly from the server interface. This enables a commissioning engineer on site to assign the physical controllers to their actual location and specific task via a browser. Because the older Codesys devices of generation V2 are also recorded via the gateway, they can also be registered and managed in the server. However, due to the lack of communication encryption, such controllers cannot be used as an Edge at the same time.

Author:
Roland Wagner is Head of Product Marketing at 3S-Smart Software Solutions.

The Codesys Automation Server

In addition to the described features for server-based administration of Codesys controllers, the upcoming Automation Server will successively provide various other useful functionalities - including, for example:

• Convenient administration and assignment of user profiles and security certificates
• Backup and restore of control applications
• Central implementation of continuous integration processes to increase the quality of application software
• Storage and evaluation of controller data