Diagnostics KNX Basic: exam questions with worked answers

Questions for the "Diagnostics" topic

1. Q01

   The ETS Bus Monitor displays telegrams at the raw frame level, whereas the Group Monitor presents them filtered and formatted at the Group Address level.

   TrueFalse

   8. Diagnostics· Monitoring-Werkzeuge· Medium

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   Correct answer

   True

   Learning tip

   This is exactly the distinction. Bus Monitor gives a raw, low-level view of every frame on the bus, useful for diagnosing low-level issues such as missing ACKs, parity errors or unexpected source individual addresses. Group Monitor gives a higher-level, business-oriented view in which values are decoded per DPT for each Group Address, ideal for verifying that pressing a button actually sends the expected telegram.

   Source: Porto KNX — Diagnostics

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2. Q02

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

   • A.The target device's individual address is already in use by another device on the bus
   • B.The target device has no power supply
   • C.The line coupler's filter table is blocking the download
   • D.The bus cable polarity is reversed

   8. Diagnostics· Adresskonflikt· Hard

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   Correct answer

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

   Learning tip

   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".

   Source: ETS troubleshooting documentation

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