Question
Among the following Group Object flags, which one must be enabled so that the device transmits a telegram whenever the object's value changes?
Answer
B — Flag T (Transmit)
The T (Transmit) flag enables spontaneous transmission of a telegram whenever the local value of the Group Object changes. C is a prerequisite that enables communication overall but does not by itself trigger sending. W allows receiving write requests from the bus. U handles updating the local value upon receipt of a Group Value Response telegram. Without T, the device can receive values but never sends its own.
Preparation tip
Mnemonic for the standard C/R/W/T/U combo: C enables communication; R responds to reads; W receives writes; T transmits; U updates on read-response.
All proposed choices (exam context)
- A.Flag C (Communication)
- B.Flag T (Transmit)✓
- C.Flag W (Write)
- D.Flag U (Update)
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