What does BREAK mean in real terms while using a UART?

Question

The break and error indication glows up in real terms while communicating with RS-232. Sometimes, the CTS is also will be glowing.

Due to this, the data in prints as junk for some time; later it gets corrected after a few reset of real term.

This is a screenshot showing the error:

What does BREAK mean really? What happens when there's a break?

Solution

A break condition occurs when the transmitter is holding the data line at logical 0 for too long, i.e. longer than the time needed for transmitting a start bit and the (usually 8) data bits. Possible causes:

The transmitter can send a break deliberately, as an out-of band signal, e.g. to signal the beginning of a data packet, like in the LIN protocol.

It can occur when the transmitter is sending at a lower speed as the receiver is expecting. Perhaps its clock is not properly initialized.

Of course it can be caused by a noisy or otherwise bad connection.