Question

During a download, ETS returns the error "Address conflict". What is the most likely cause?

KNX BasicLearnDiagnosticsHard
Answer

A — The target device's individual address is already in use by another device on the bus

An "Address conflict" during a download means that two devices respond to the same individual address. This typically happens when a device already installed has the same address as the new one being programmed, or when a device has been duplicated in the project. Choice B (no power supply) would yield a timeout error, not a conflict. Choice C is incorrect because filter tables apply to Group Addresses, not to point-to-point downloads. Choice D is intrinsically wrong because the KNX TP bus cable is non-polarised, so polarity cannot be "reversed".

Preparation tip

When you hit an address conflict, isolate devices one by one (cut their power or physically remove them) or use the programming button to re-assign a new address — there is no shortcut.

All proposed choices (exam context)
  1. A.The target device's individual address is already in use by another device on the bus
  2. B.The target device has no power supply
  3. C.The line coupler's filter table is blocking the download
  4. D.The bus cable polarity is reversed
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Last updated: 19 May 2026

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