[Development] modbus over serial port on windows 7 ?

Karsten Heimrich Karsten.Heimrich at qt.io
Thu Jun 2 21:13:57 CEST 2016


just a short note, we already added API for overwriting the timeout in 5.7. See http://doc-snapshots.qt.io/qt5-5.7/qmodbusrtuserialmaster.html#setInterFrameDelay But as seen here http://code.qt.io/cgit/qt/qtserialbus.git/tree/src/serialbus/qmodbusrtuserialmaster_p.h#n294 we missed to update some parts.


From: Development <development-bounces+karsten.heimrich=qt.io at qt-project.org> on behalf of Denis Shienkov <denis.shienkov at gmail.com>
Sent: Thursday, June 2, 2016 4:53:49 PM
Cc: development at qt-project.org
Subject: Re: [Development] modbus over serial port on windows 7 ?

> You can't do that with timing on a non-real-time task.

Quite so! The Modbus spec has been written for the PLC's, where are used the Real-Time OS (or for 'bare metal' hardwares).

I have added some ideas, how to avoid it to QTBUG-53767


2016-06-02 16:02 GMT+03:00 Thiago Macieira <thiago.macieira at intel.com<mailto:thiago.macieira at intel.com>>:
On quinta-feira, 2 de junho de 2016 11:42:27 BRT Alexander Blasche wrote:
> Certain error cases can only be detected if you make assumptions about
> timeouts. Otherwise there is no way to determine where one packet stops and
> where the next one begins.

You can't do that with timing on a non-real-time task. Forget it.

If this bus requires that, make sure to do the packet splitting in a real-time
*kernel* task.

Thiago Macieira - thiago.macieira (AT) intel.com<http://intel.com>
  Software Architect - Intel Open Source Technology Center

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