Thin Clients Eliminating Plant Floor PCs |

Thin Clients Eliminating Plant Floor PCs

February 052013
Thin Clients Eliminating Plant Floor PCs

February 2013

By Bill Lydon, Editor

Thin Clients are starting to replace PCs on the plant floor because they are easier to maintain and have lower lifecycle maintenance cost. Before the PC, automation systems were built using a single large computer with “dumb terminals” (display and keyboard) connected to them. The big drawback of these terminals was that they required home run wiring to the control room and were a burden on the automation system computer. Later PCs were used for HMI (Human Machine Interface) and other software to essentially distribute the functions of industrial automation systems. More recently, with higher speed and more reliable Ethernet networks, lower cost more powerful computers, and virtualized systems, the use of Thin Clients has become effective.

A Thin Client (sometimes also called a lean or slim client) is typically a diskless and fan less computer which depends heavily on a server.  A “fat client” typically has resident HMI, database, alarming, and other software running on disk-based PCs on the plant floor. In the past, dumb terminals were used in automation systems only in special applications with terminal sever functions of operating systems. They were not efficient for this purpose and required very expensive computers to run properly. The cost of powerful computers, particularly multicore-based hardware, has dropped dramatically and the use of virtualized systems is making Thin Clients an excellent choice for use in automation systems.

The most common type of Thin Client is a diskless and fan less computer terminal with integrated Ethernet which concentrates solely on providing a graphical user interface to the end-user. The remaining functionality including computations, alarm management, historic database, and analysis is provided by the server. A major advantage of thin clients is they have no wearing mechanical parts, such as a fan or hard disk, which makes them virtually maintenance free.

Thin-client computers are easily maintained and software is administered at the server, reducing total cost of ownership. All software and hardware upgrades, security policies, application changes, etc. can be made at the server and immediately take effect throughout the automation system. The reduced maintenance of Thin Clients ultimately saves labor that can be used more productively. Remote configuration software enables the Thin Clients to be managed centrally via the network, for example for a parallel firmware update. Since the automation software is all resident at the server, another large savings is that software updates, patches, etc. are all done centrally in a secure environment. The use of full function PCs running industrial automation software throughout a plant requires a great deal of configuration control and the software requires a great amount of update and patch time. Computing and software application backup and redundancy can also be accomplished at a lower cost at servers rather than at every PC in a plant.

Thin Clients also lower the risk of cyber security issues since there is no hard drive or floppy drive.  As a result, Thin Clients are protected from the use of unauthorized software or the introduction of viruses. Data cannot be copied to a disk or saved to any other location than the central server. Centralized processing makes it easy to manage and monitor system access and enforce security policies and procedures, so that internal security risk is minimized.

Thin clients also use anywhere from 8-10 watts of power, compared to 150 watts for PCs. These green benefits help companies save upwards of nearly 85% on their power costs.

Lower cost multiprocessor computers and virtualization are enabling the use of properly designed Thin Client systems practical - improving automation system availably and production uptime.

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