Everyone knows about virtual drives and even virtualized computers. These images of physical devices, in this case hard disks or Windows PCs, help us to use their function. And they do so without the devices actually being there. The images are created by software on computer architectures that are powerful enough. In IT, such virtualizations are useful for increasing the data security of systems through sensible limits on access, as well as for making mutually independent configurations possible for different users and applications.
The same applies to virtual controllers: First of all, powerful hardware is required as a substructure. Even if the PLC is abstracted, it must of course be hosted and executed somewhere. In this respect, the virtual PLC is initially no different from an industrial computer with an operating system and a SoftPLC installed on it. However, in order to be able to operate such virtual controllers on any number of hardware devices and independently of each other, a further abstraction must be made. Software containers or hypervisors are suitable for this purpose.
They separate the hardware and the operating system running on it. To do this, the user defines the functionality and performance of a container or virtual machine in container descriptions or configuration files – including the corresponding configuration for the SoftPLC, such as CODESYS Virtual Control SL. In addition, the access to hardware resources for the container are specified. This is mandatory in order to be able to implement I/O accesses from the controller. Ethernet-based communication protocols and fieldbus systems are particularly well suited. In this way, virtual LAN ports can be defined in the container, which are linked to physical ports in the container description.
Thanks to hardware-supported virtualization, this is possible with high performance on modern systems. This means: Due to a better differentiation of processes and hardware support, even better real-time values can be achieved than with SoftPLCs running natively on the host system.
CODESYS has been offering hardware-independent Soft PLCs for over 20 years and has continuously been expanding its products. Currently, CODESYS offers hardware independent Soft PLCs with and without real time for Windows, as well as Soft PLC solutions for Linux x86 and ARM based systems.
The CODESYS Virtual PLC is a more advanced product towards the future. It allows CODESYS Soft PLC to run in a virtual environment without the need for a device. Instead, the appliance is replaced by containers and hypervisor technologies.
The CODESYS virtual PLC can be installed multiple times on one device and has no hardware requirements. You are connected to the world of automation via a virtual LAN. CODESYS currently delivers CODESYS controls in Docker containers to pilot customers.
CODESYS will soon release solutions based on hypervisor technology, for example to easily install CODESYS Control on a server.
ADVANTAGES
- Huge cost savings in hardware acquisition, cabling, operation and maintenance
- Machine and plant operators can provide and manage the hardware platform themselves.
- Independence of hardware and hardware manufacturers.
- Easy scaling through dynamic control instantiation and the ability to expand hardware independently of software
- Security by design by distributing tasks to several independent control instances with powerful intercom
- Interoperability with other services (“microservices”)
- Simplified deployment of security updates
- Central maintenance and care of virtual controls with the technologies and comfort of IT systems, including application updates