LazSerial error
lazarus / 62-General

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HatForCat · 2017-01-30 21:46

Just started getting this error when trying to Close the Serial Port.

Project SerialData raised exception class 'External: SIGSEGV'.
 In file 'gconv_close.c' at line 35

I thought I had fixed it by using "Ser1.Active:=False;" instead of
"Ser1.Close;" but I am just getting the error less often, not fixed.

Anyone have thoughts on how to actually fix this?

Code: [Select]procedure TfrmMain.btnCommOpenClick(Sender: TObject);
begin
  if Comm1.Active then Exit;
  try
    Comm1.Device:=edSerial.Text;
    Comm1.Open;
    CommStrRaw:=Comm1.ReadData;  // Clear anything in the Buffer
    CommStrRaw:='';
    memoSerial.Clear;
    if Comm1.Active then
    begin
      pnlSerial.Color:=clLime;
      memoSerial.Lines.Add('OPENED '+Comm1.Device);
    end;
  except
    ShowMessage('FAILED to OPEN '+Comm1.Device);
    memoSerial.Lines.Add('FAILED OPEN'+Comm1.Device);
  end;
end;

procedure TfrmMain.btnCommCloseClick(Sender: TObject);
begin
  if not(Comm1.Active) then Exit;
  Comm1.Active:=False;  // <--- This used to be Comm1.Close;
  pnlSerial.Color:=clRed;
  memoSerial.Lines.Add('CLOSED '+Comm1.Device);
end;

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Jurassic Pork · 2017-01-31 05:44

hello,
strange, because the close procedure of TLazserial  is :
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TLazSerial.Close;begin  Active:=false;end;
i have no problem to open and close port with the sertest example  of
TLazserial on Ubuntu 14.04 LTS 64 bits Lazarus 1.6 FPC 1.3.  Have you
the problem with this example ?
What are you doing in your program ?
Have you tried the flush and purge methods before closing the port ? :
Quoteprocedure Flush; virtual;

Waits until all data to is sent and buffers are emptied. Warning: On
Windows systems is this method returns when all buffers are flushed to
the serial port controller, before the last byte is sent!
===========================================================
Public    procedure Purge; virtual;

Unconditionally empty all buffers. It is good when you need to
interrupt communication and for cleanups.
flush is used in the deviceclose  procedure (called when you put
active to false ) :
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TLazSerial.DeviceClose;begin  // flush device  if
FSynSer.Handle<>INVALID_HANDLE_VALUE then begin    FSynSer.Flush;   
FSynSer.CloseSocket; //   FSynSer.Purge;  end;    // stop capture
thread  if ReadThread<>nil then begin   
ReadThread.FreeOnTerminate:=false;    ReadThread.MustDie:= true;   
while not ReadThread.Terminated do begin     
Application.ProcessMessages;    end;    ReadThread.Free;   
ReadThread:=nil;  end;   // close device  if
FSynSer.Handle<>INVALID_HANDLE_VALUE then begin    FSynSer.Flush;   
FSynSer.CloseSocket;  end;end;          
Friendly, J.P


Edit : TlazSerial is now in Github here with a 0.2 version :
QuoteV 0.2  01/2017 : BaudRates for UNIX fixed - synaser files units
renamed (with laz prefix) to avoid conflict with the original synaser
files.
                 scan port for linux improved

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Thaddy · 2017-01-31 07:53

I have no problems either.

Can you adapt your exception handling a bit and report back which
exception there actually is?
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i // NOT
thisShowMessage('FAILED to OPEN '+Comm1.Device);//But THIS at a
minimum:on e:Exception do  // needs sysutils, of course 
ShowMessage(e.message,'|','FAILED to OPEN '+Comm1.Device); That will
give you more meaningful exception information.

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HatForCat · 2017-01-31 20:31

Thanks for the replies, bit nothing works. It bombs before it gets to
handle the exception.

I have put Try/except in everything associated with the Comm1 and
still it gives the " In file 'gconv_close.c' at line 35" error. Never
triggering an exception.

I can't seem to trap it with stepping through either. It appears to be
right after the Comm1.close; statement but before the very next line
of code is processed. It never gets to change the Panel color or to
the "except".

{edit} Just saw a "Run Error 216" flash by. What is that? {/edit}

Code: [Select]    try
      Comm1.Close;
      pnlSerial.Color:=clRed;
      memoSerial.Lines.Add('CLOSED '+Comm1.Device);
    except
      on e:Exception do  // needs sysutils, of course
        ShowMessage(e.message+'|'+'FAILED to CLOSE '+Comm1.Device);
    end;

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molly · 2017-01-31 21:07

Quote from: HatForCat on January 31, 2017, 09:31:29 pmIt appears to be
right after the Comm1.close; statement but before the very next line
of code is processed.
Put up some showmessage between the lines, just as you did for the
exception. It is annoying to click away those messageboxes but will
tell you which line exactly bails out.

Quote{edit} Just saw a "Run Error 216" flash by. What is that? {/edit}
Runtime errors:
Quote216 General Protection fault
The application tried to access invalid memory space. This can be
caused by several problems:
1 Dereferencing a nil pointer.
2 Trying to access memory which is out of bounds (for example, calling
move with an invalid length).
Meaning you are accessing something that isn't there anymore (or never
wasn't).

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HatForCat · 2017-01-31 22:25

Nothing to do with LazSerial a such. It was Lazarus not handling an
array being passed-by-reference.

It worked fine normally when data was streaming in and out. But it
seems that **sometimes,** when the Serial was closed abruptly, the
array was caught part way through an iteration of indexes. I put in a
"delay(300);" after each time the array was being passed and solved
the problem.

I changed the array to Global so it didn't need passing and it all
went away. I did not want to leave the Delay-kludge in place. A bit of
a weird Lazarus-bug I suspect, but have no inclination to delve into
why/where/how.

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Thaddy · 2017-02-01 05:53

What we would do is pass the array as const, not declare it global.

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HatForCat · 2017-02-01 16:47

Quote from: Thaddy on February 01, 2017, 06:53:50 amWhat we would do
is pass the array as const, not declare it global.
OK, thanks, but Global was actually the way I had back in Delphi, I
should have left it as was and not try to "fix" it with some
streamlining when I moved to Ubuntu and Lazarus