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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:

Screenshot showing error

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

Jonathan Leffler
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MVA
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  • In a nutshell a BREAK condition is a Frame Error. It means that parity bit and stop bits are not matched. Usually is used as start packet condition holding the line (TX) asserted for a certain time. – LPs May 31 '16 at 08:26
  • Thanks LP..for the comment.. – MVA May 31 '16 at 08:45
  • Thanks Willie i will try to improve the the content quality – MVA May 31 '16 at 08:46

1 Answers1

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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.

followed Monica to Codidact
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    _data line low_ . Not true at all. It is **data line at logical 0**. – LPs May 31 '16 at 08:45
  • @LPs Kind of depends on which side of the RS232 transceiver you take a peek at. – Lundin May 31 '16 at 08:48
  • Thanks for all your co-operation..It would also be very helpful if the user could know by which method we could avoid these above mentioned error – MVA May 31 '16 at 08:58
  • @Lundin I'm not getting you. RS232 talking to send a BREAK you must move from logical 1 (below -3V) to logical 0 (more than +3V) and hold the line there for at time that assure the receiver to trigger a frame error. The minimum time is obviously based on the current baud rate. Another matter is to see signals of UART (TTL) where all thing can be done. – LPs May 31 '16 at 08:58
  • @LPs I just meant that if you peek on the UART side rather than the RS232 side, then pulling data line low is the same thing as logical 0. – Lundin May 31 '16 at 09:01
  • @Lundin Well, yes, true. I don't know if there are RS232 transceiver with inverted signals on TTL side. – LPs May 31 '16 at 09:11
  • @MVA It is too broad to give such a description. Frame error can be: voluntary action, a line noise problem, a mismatch of baudrate caused by thermal derating and other tons of causes. – LPs May 31 '16 at 09:25
  • Thanks LP,At least a small idea i got it – MVA May 31 '16 at 10:23