Virtualized Automation

Virtual Automation System are classified as a System or Collection of Systems that mimick the function of device, that does function traditionally as a single unit. All modern SCADA Systems can be classified as "Virtualized". Virtualization enables primitive devices to gain additionally functions and behave like a integrated unit, without being one.

Virtualized automation systems work by enumerating Physical interfaces to primitive devices, processing the resources and Creating complex schemas and integration functionality.

Key factors that matter for Virtualization

• Mapping of primitive Resources (Channels)
• Combination of primitive Resources to a more complex resource
• Scripting, Scheduling and Functions
• Events and Event handling
• Monitoring of resources
• Versatile abstraction interfaces
• Visualization and remote control

These functionality can be combined with partial autonomy on the devices, wich is most often required on security functions like interlocking. Virtualized Systems then have no full autonomy on the devices but do constantly monitor and request the device, to perform actions whenever possible.

Problems and countermeasures

Bottlenecking

Slow field bus systems, bad planning and poor device configuration (i.e. talkative devices) can sometimes lead to problems like bottlenecking, that slows down the links to the devices when flooded with informations. To counter those issues, systems must be planned and tested considering maximum throughput on the links. Some high throuput bus systems or those who establish secondary physical links are usually not affected by bottlenecking.

Remedy: Cautious planning, secondary data paths, high speed transceivers and line splitting.

Single point of Failure

A SCADA System that claims full autonomy can represent a single point of failure, as the system will not operate when the automation system or software is unavailable "Crashed". Most automation Systems include watchdogs, automatic restarting or even fallback systems, that cover for a failed system. Fallback systems are required for Places where a faulire can present damage to Objects.

Remedy: Redunancy Systems (Fallback) with automated handover.

Limitations

History has proven that safety functions like hardware interlocks must never implemented by protentially unreliable computer systems. as only specialized and certified computer systems may implement these features, most automation system require to attach special hardware devices for safe and conformant functionality in applications where malfunction present danger to life or goods.