CyberCertPrepOT Security FundamentalsOT Fundamentals: Network Architecture & ProtocolsMEDIUMFree question
On a Modbus RTU trunk a master sends a write to slave address 0. Which behavior does the protocol define for that frame?
- A.The gateway rejects it with exception code 01 for slave 0
- B.The write is queued until the master polls the next slave
- C.Slaves on the line execute the write with no reply sent
- D.The slave with address 247 takes it for the default unit
Why C is correct
Address 0 is the broadcast address. Slaves act on the write but must not answer, so the master gets no confirmation. That is why broadcast writes are hazardous when a rogue master is present.
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