ISA Certified Automation Professional (CAP) program

  • Certification Review

Certified Automation Professionals (CAPs) are responsible for the direction, design, and deployment of systems and equipment for manufacturing and control systems.

CAP question

In a thin client (distributed) HMI architecture, the data is typically presented on the client PC via the use of:

A. Client software loaded on the client PC in a special directory
B. Web browser or automatically-loaded applet
C. SQL query builder
D. Microsoft Office applications

CAP Answer

The answer is B: "Web browser or automatically-loaded applet".

In thin client architectures, a “light-weight” computer is used as the HMI. The thin client is optimized for establishing a remote connection with a server-based computing environment. The server does most of the work, which can include launching software programs such as web pages or applets, performing calculations, and storing data. The only application running on the thin client is a small applet or web-browser. Therefore, the hardware can be configured without the need for high-end CPU’s or large disk drives.

Since the processing is done on the server in a protected environment, failure of a thin client does not affect the control software. Another thin client can be substituted without major reconfiguration and often within minutes.

Reference: Trevathan, Vernon L., A Guide to the Automation Body of Knowledge, 2nd Ed., 2006

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