Table 1
Virtualization is directly applicable to server-based CPAS functions
Virtualization Benefits in CPAS
Since virtualization today can only be applied to some parts of process automation systems, it can be difficult to assign specific economic value to the technology. Virtualization plays an important role wherever server hardware is used in the automation system. This is at levels 2 to 4 of the ISA-95 manufacturing model. Today’s automation suppliers offer system configurations that feature server consolidation. Multiple HMI machines and other application servers are replaced by virtual machines. A small number (usually one or two) of more powerful hosts support these virtual machines. Besides being more powerful, the new servers incorporate levels of redundancy with respect to power, storage, compute, and network resources.
Server consolidation benefits include removal of physical equipment, freeing rack or panel space in congested control areas. Power requirements and system administration burden are also reduced (though the remaining administration work is technically more complex).
The largest benefit to end users of server consolidation in process automation systems is the de-coupling of the automation software from specific configurations of PC or server hardware. For years, many HMI and other automation system functions have been implemented on PC hardware. Plant owner-operators and automation suppliers have struggled to support these systems due to the short lifecycle of PC products. By virtualizing such a system, it can be more easily supported once replacement hardware is no longer available. This higher degree of hardware independence helps extend automation system life and reduces production interruptions due to automation system upgrades.
At lower levels (1-2) in the ISA-95 model, automation functions are implemented in embedded systems (e.g., process controllers, process I/O equipment or field devices) that are managed by a real-time OS.
While these devices can be simulated or emulated, strictly speaking they cannot be virtualized as-is. Instead, their embedded software must be modified and/or ported to some degree to operate in a virtual machine environment. Most automation suppliers have developed products that now provide this functionality.
For the field devices and actuators at level 1 of the ISA-95 model, there is not much to report at present about virtualization. Simulation software/hardware is available for some field networks. Several technologies are becoming available (EDDL, FDT, FDI) for managing field device parameterization, configuration and diagnostics. However, the commissioning of field devices remains largely a field activity and has not yet benefited from virtualization or simulation to the same degree as other areas of process automation systems.