[Gambas-user] using events of serial ports for reading how_?

Mon Aug 6 23:10:12 CEST 2018

um ok make sense that if there's already a event handler why use the manual
reading..

the problem its that sometimes i made manual reading an get extra data that
are not in the event handler (yep sound quite strange) due i'm managing a
fiscal kit printer device

i'll try to use your semaphore, but there's another way maybe using the*
CTSChange <http://gambaswiki.org/wiki/comp/gb.net/serialport/.ctschange>*
*DCDChange <http://gambaswiki.org/wiki/comp/gb.net/serialport/.dcdchange>*
 *DSRChange
<http://gambaswiki.org/wiki/comp/gb.net/serialport/.dsrchange>*  *DTRChange
<http://gambaswiki.org/wiki/comp/gb.net/serialport/.dtrchange>*  *RNGChange
<http://gambaswiki.org/wiki/comp/gb.net/serialport/.rngchange>*  *RTSChange
<http://gambaswiki.org/wiki/comp/gb.net/serialport/.rtschange>*
??

Lenz McKAY Gerardo (PICCORO)
http://qgqlochekone.blogspot.com

El lun., 6 de ago. de 2018 a la(s) 13:41, T Lee Davidson (
t.lee.davidson at gmail.com) escribió:

> You will have problems if you try to utilize both an event triggered
> serial port read and a manual read.
>
> The SerialPort.Read event is triggered when there is data available to be
> read. If you read that data in the event handler, the
> port is cleared and there will be no data available to a manual read.
>
> If you want to manually read the port, then you should not read the data
> from it in the SerialPort.Read event handler. Perhaps
> you do not even need to implement that event handler.
>
> I could be incorrect since I haven't verified this. But, it seems logical
> to me that Stream.Blocking would be False by default
> otherwise an attempt to read the port would hang the application until
> data is available and that should not be a default behavior.
>
> I can think of two ways to implement manual reading.
>
> 1. Do not implement a SerialPort.Read event handler, ensure that
> Stream.Blocking = False, and simply read the port manually
> understanding that there may be no data available. In this case READ would
> appear to do nothing, but the application would not hang.
>
> 2. Use the SerialPort.Read event handler to set a flag indicating that
> data is available and read that flag in your Sub rp()
> function. For example:
>
> Private PortDataAvailable As Boolean
>
> Public Sub SComm_Read()
>         PortDataAvailable = True
> End
>
> Public Sub rp()
>         If myDataAvailableBoolean then
>                 ' Do the port reading stuff
>                 ' Read port blah blah blah
>                 ' All data has been read
>                 PortDataAvailable = False
>         Else
>                 Print "No data available"
>                 Return
>         Endif
> End
>
>
> ___
> Lee
>
>
> On 08/06/2018 12:05 PM, PICCORO McKAY Lenz wrote:
> > OK hans, and tobias, yes the code in my first mail last week was bad,
> > now i understant some problems when i read agains the printert
> > but i need and i want a manual read funtion "also": so i have now:
> >
> > the read event for the port, as documents suggest "is triggered"
> > when data "can be read" so if there's some data to read or available
> > the event will be executed by itselft, but i want also a manual "rp"
> method
> > that read also the port manually, at this point i dont know
> > if will be sync or async, i have a "sale" class that will be polled into
> a form,
> > but as Tobias said i used the Scom_Read
> > but still need a manual read funtion due the inherits so i have :
> >
> > 1) the read event:
> >
> > ' this event will be triggered in read operations by the stream when
> data its available
> > Public Sub SComm_Read()
> >    dim buffers as string = ''
> >   Read #SComm, buffers, Lof(SComm)
> >    dataread &= buffers
> > End
> >
> > 2) here, how can i code a read manual operation do not conflict if
> there's already an operation triggered by teh read event?
> >
> > i used some code proposed by Tobias but:
> >
> > '' generic read port buffer data
> > Public Sub rp()
> >    dim  start as date = Now
> >    dim buffers as string = ''
> >   Do
> >     Wait 0.1
> >     Read #SComm, buffers, Lof(SComm)
> >     dataread &= buffers
> >   Loop Until DateDiff(start, Now, gb.Millisecond) > 500
> > End
> >
> > now i have the problem of locking, as Tobias said I not even sure how
> Read
> > behaves when Lof is zero or if the read are just triggered at same time
> the rp was invoqued!
> > so then reading would block.
> >
> > i dont know how to use the SComm.Blocking = False to make manual polling,
> >
> >
> > Lenz McKAY Gerardo (PICCORO)
> > http://qgqlochekone.blogspot.com
> >
> >
> > El lun., 6 de ago. de 2018 a la(s) 09:59, PICCORO McKAY Lenz (
> mckaygerhard at gmail.com <mailto:mckaygerhard at gmail.com>) escribió:
> >
> >     El lun., 6 de ago. de 2018 a la(s) 09:52, Hans Lehmann (
> hans at gambas-buch.de <mailto:hans at gambas-buch.de>) escribió:
> >
> >         have a look at the chapters and the projects... under
> https://www.gambas-buch.de/doku.php?id=k24:k24.1:k24.1.5:start!
> >
> >     THANKS HANS! now reading...
> >      isend this mail to the list.. maybe you send too quickly and
> forgett to do!
> >
> >
> >
> >
> >
> > ----[ Gambas mailing-list is hosted by https://www.hostsharing.net ]----
> >
>
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>
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