MAY-JUN 2019

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mounted terminal, or even mobile devices. ● Easier development: Factory develop- ment and testing activities can be car- ried out on a VM environment hosted anywhere; actual field-deployed hard- ware is not required. This ability is very significant for OEMs and SIs. ● Rapid integration: Transferring devel- opment configurations to production system thin clients is convenient and quick, especially compared to config- uring multiple standalone physical servers and PCs. ● Simplified maintenance: Centralized control of VMs is easier than main- taining widely distributed assets that would otherwise require in-person attention for updates and security patches. ● Scalable: Thin-client architectures are readily scalable and benefit from cen- tralized standardization and reuse. ● Verified: Best practices can be estab- lished and maintained across de- ployed devices, for consistency, reli- ability, and repeatability. The preceding benefits are only the basics that standard thin-client config- urations provide. Just as the industrial hardware experience can be improved by using OT-optimized servers, so too can the thin-client software experi- ence. Thin-client manager software optimized for industrial users is avail- able (figure 3) and adds the following to enhanced thin-client management: ● Redundancy: VM sessions are redun- dant and can fail on the server side to keep the thin clients running. ● Shadowing: Administrators or termi- nals can view and operate another terminal. ● Session control: Multiple sessions can be combined and arranged on a single display. ● Role-based control: Organizations can control and manage the content de- livered based on login. Certain users can view and control only what they are authorized to see and change. ● Locational control: Content can be tailored to the location of the thin client. Next, let's look at the architectural shift that enables thin-client deployment. PCs. And now, the growing trend to in- stall control and visualization comput- ing assets out on the factory floor, or even on skids and machines, makes this an even more complex proposition. A better solution is to maintain cen- tralized redundant server hardware at the core, but use it to host automation- related VMs, while serving up HMI appli- cations to remote thin clients as needed. The servers can be located in a secure computer room or another protected yet remote location like a control room or electrical room. Redundant servers can be traditional IT-centric style or OT- optimized versions tailored for operating in an industrial role (figure 2). Thin-client technology is the pre- ferred way to reliably deploy and manage distributed HMIs and vir- tual machines throughout a facility, especially those systems supporting mobile device clients. This means any industrial automation VM or applica- tion can be viewed and operated at any PC, panel-mounted terminal, or mobile device connected to the com- pany intranet. This thin-client architecture brings a better experience at the edge and is far more maintainable by OT personnel responsible for the industrial automa- tion core. Some benefits are: ● Inexpensive edge: Edge-located thin clients are lightweight in terms of hardware resource requirements and relatively inexpensive. They can be quickly replaced and reconfigured. ● App-serving flexibility: HMI appli- cations can be served to any sort of remote device, such as a PC, panel- Converging IT and OT business units is not the end game, but industrial edge deployments must successfully coordi- nate both groups. Generally speaking, IT personnel are not trained to work with industrial-specific products. In fact, the industrial network usually must be carefully firewalled from the business network. OT depends on VMs and thin-client technologies, but per- sonnel are often not equipped to man- age extensive IT-centric systems. A workable middle ground is to package IT-centric hardware and soft- ware deployment capabilities into OT-focused platforms. In this way, OT personnel can readily operate and maintain IT technologies. Thin clients aid the edge and core Traditional automation computing ar- chitectures have included both distrib- uted and centralized elements. Purely OT devices, such as PLCs and PACs, have been installed at the industrial edge to interact with field devices like motors, valves, and sensors for gath- er ing information and performing detailed control. These OT assets con- tinue to become more capable. They still play an important role. Crossing over into the IT realm, in- dustrial automation SCADA and HMI servers formed a "core" above the OT devices, networked to desktop PCs situ- ated throughout the facility as needed. Although this IT-centric server and PC arrangement is functional, this configu- ration can be cumbersome to manage, because it is relatively expensive to de- ploy and maintain numerous remote AUTOMATION IT 32 INTECH MAY/JUNE 2019 WWW.ISA.ORG Figure 2. Purpose-built edge computing platforms, like this Stratus ztC Edge system that operates as a redundant pair of nodes, can withstand challenging environments and are easily deployed and maintained by OT personnel.

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