Purpose of a start bit in RS232 serial communication protocol is
19972024
Purpose of a start bit in RS232 serial communication protocol is
- A.
to synchronize receiver for receiving every byte
- B.
to synchronize receiver for receiving a sequence of bytes
- C.
a parity bit
- D.
to synchronize receiver for receiving the last byte
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Correct answer: A
When the RS-232 communication line is idle, it stays in a high voltage state (called the MARK state, typically representing a binary 1).
The Trigger: When a transmitter wants to send a data packet, it drops the line voltage to a low state (called the SPACE state, representing a binary 0) for exactly one bit duration. This high-to-low transition is the Start Bit.
The Action: The receiver constantly monitors the line for this drop in voltage. The moment it detects the start bit, its internal clock resets and starts counting to sample the incoming data bits at the correct intervals.
The Scope: RS-232 frames data on a per-byte basis (or per character basis). Each individual byte is wrapped in its own start bit at the beginning and stop bit(s) at the end.
Therefore, the purpose of the start bit is to synchronize the receiver's clock at the start of every single byte.