CyberCertPrepOT Security FundamentalsOT Fundamentals: Securing Industrial Control SystemsMEDIUMFree question
An IDS alerts on Modbus function code 15 sent from an unfamiliar host to a PLC controlling pump valves. What does that code do?
- A.It sets the states of several discrete outputs at once
- B.It uploads the stored ladder program to the requester
- C.It reads a block of holding registers from analog inputs
- D.It restarts the communication stack of the target device
Why A is correct
Function code 15 is Write Multiple Coils, which sets many discrete outputs at once and can open or close valves. Reading registers is code 3 and Modbus has no standard program upload.
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