How to send a Break signal ( serial-node)

General
1

Hello All, I'm new with Node-Red and found that is a very interesting platform. I'm trying to log data from a serial communication device, but my problem is that to get a full set of data from the device I must sent to this a command that Must start with a Break Signal of at least 2ms. Some one could help me on how to achieve this? I already search and found many projects with serial-node, but no one that perform this activity.
This is a great forum, I will appreciate any help. Thanks

2

Hi,
Sorry to be dense, but what is a break signal ? How do you send it normally without Node-RED ?

3

The Break signal must be of a duration longer than the time it takes to send a complete byte plus Start, Stop and Parity bits. In my case, at least 2ms.
In RS232 a signal called a Break , which is caused by sending continuous Spacing values (no Start or Stop bits). When there is no electricity present on the data circuit, the line is considered to be sending Break .
Is a long time that I don't do nothing like this, but I used some Simple routines on little's projects with PICs ( microprocessors).
No clues to How to do this here...

4

This is an example of what I need:

SetCommBreak(port)
    Sleep(2);  // 2 milliseconds - assuming 9600 baud. Pro-rata for others
    ClearCommBreak(port)

But as I said before I don't know from where start, thank for your time!

5

OK - I'll admit I have never seen that before (despite playing with serial ports for more years than I care to recall) - and so no I know we don't support that right now. Would need digging into and working out how to tell the node to send that (and maybe other things like that) in a way that doesn't break existing users.
Feel free to raise an issue against the serialport node - but I can't promise when we'll get a chance to look at it. (suggestions / help wanted ! )

6

If my memory serves me correctly I believe that has to be handled at the UART level, so first you would have to find out if your hardware supported it. I don't know whether USB-Serial UARTS will do it, for example. There used to be serial devices that used a break input to reset things, but I don't remember seeing that for years.

.. following a quick google it appears the FTDI chips do support break.

7

Yes the serialport library does seem to support it, but as I said we need to work out a way to a)call it in a sensible way and b) do that in a way that doesn’t break anything else.

8

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