When you consider wireless media for an IACS application, which percentage of traffic should be reserved for HMI and maintenance traffic, such as RSLinx, programming tools, and IT management?

Question

Options

• A3%
• B60%
• C20%
• D85%

• A
  8% (3)
• B
  13% (5)
• C
  74% (29)
• D
  5% (2)

Explanation

In IACS wireless network design, 20% of bandwidth should be reserved for HMI and maintenance traffic - tools like RSLinx, programming software, and IT management - to ensure those critical support functions don't compete with or disrupt real-time control traffic. This guideline comes from industrial networking best practices (notably Rockwell Automation/Cisco IACS design guides), which recommend an 80/20 split: 80% for control traffic, 20% for overhead and management traffic.

Why the distractors are wrong:

• A (3%) is far too low - reserving only 3% would starve HMI and diagnostic tools of the bandwidth they need during peak maintenance activity.
• B (60%) over-allocates to management traffic, leaving insufficient headroom for the deterministic control traffic that IACS depends on.
• D (85%) nearly inverts the ratio entirely and would be a critical design flaw, leaving almost no bandwidth for actual control communications.

Memory tip: Think "80/20 rule" - 80% for control (the main job), 20% for management (the support crew). If you remember this from general networking/business efficiency principles, it maps directly to IACS wireless design.

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