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AutoQuiz: What Is the Length Limitation for Fast Ethernet Cable?

The post AutoQuiz: What Is the Length Limitation for Fast Ethernet Cable? first appeared on the ISA Interchange blog site.

AutoQuiz is edited by Joel Don, ISA’s social media community manager.

Today’s automation industry quiz question comes from the ISA Certified Automation Professional certification program. ISA CAP certification provides a non-biased, third-party, objective assessment and confirmation of an automation professional’s skills. The CAP exam is focused on direction, definition, design, development/application, deployment, documentation, and support of systems, software, and equipment used in control systems, manufacturing information systems, systems integration, and operational consulting. Click this link for information about the CAP program. The following question comes from the CAP study guide, Performance Domain II, Definition: Identify customer requirements and complete high-level analysis of the best way to meet those requirements.

What is the recommended limitation in meters for the length of a “fast Ethernet” (100 Megabits/second) segment on twisted pair cable?

a) 10
b) 100
c) 300
d) 350
e) none of the above


<span class="collapseomatic " id="id3395" tabindex="0" title="Click Here to Reveal the Answer” >Click Here to Reveal the Answer

Because of the high speed of “fast Ethernet,” the use of twisted pair cable is limited to 100 meters (330 feet). 10 meters would limit installations unnecessarily. 300 meters and 350 meters would exceed recommendations substantially, which could potentially cause signal errors.

The correct answer is B, 100.

Reference: Berge, Jonas; Fieldbuses for Process Control: Engineering, Operation, and Maintenance

Source: ISA News