FreePascal bindings for National Instrument oscilloscope/digitizer cards

[mig-31]

Hi,

I found bugs in niscope_win32 bindging and correted it. Please find update in the attachment.

But I how troubles with testing it on NI-PXI5122 card.
Same code works on console application, but crashed in GUI on function CheckError(niScope_AutoSetup(vi),vi); with External:SIGSEGV error.
Now I don't know the way how to solve it.
Thanks for showing the way where is a bug (FPC 2.6.0 Lazarus 1.1 win32).

Console application code:

Code: [Select]

program test;

{$mode objfpc}{$H+}

uses
  {$IFDEF UNIX}{$IFDEF UseCThreads}
  cthreads,
  {$ENDIF}{$ENDIF}
  Classes, niscope, visatype,sysutils
  { you can add units after this };
var
  resourceName:string = 'Dev3';
  vi:ViSession = VI_NULL;
  actualRecordLength:ViInt32;
  actualSampleRate:viReal64;
  data:array of viReal64;
  channel:string='0';
  wfmInfo:niScope_wfmInfo;
  i:word;

procedure CheckError(AErrorCode: ViStatus; Avi: viSession);
var
  errorMessage:string;
begin
  SetLength(errorMessage,MAX_ERROR_DESCRIPTION);
  if (AErrorCode<>VI_SUCCESS) then begin
    niScope_GetErrorMessage(Avi,AErrorCode,Length(errorMessage),@errorMessage[1]);
    writeln(errorMessage);
    if Avi<>VI_NULL then begin
       niScope_close(Avi);
    end;
    Halt;
  end;
 end;
begin
  //Init Session
  CheckError(niScope_init(@resourceName[1],NISCOPE_VAL_FALSE,NISCOPE_VAL_FALSE,@vi),vi);
  writeln('Pointer value:' ,vi);
  //auto setup measurement
  CheckError(niScope_AutoSetup(vi),vi);
  showMessage(vi);
  //read the actual record length and sample rate setuped by autosetup
  CheckError(niScope_ActualRecordLength(vi,@actualRecordLength),vi);
  CheckError(niScope_SampleRate(vi,@actualSampleRate),vi);
  writeln('Record lenght: ',actualRecordLength,'. Sample Rate: ',actualSampleRate);
  //set buffer length(array) and read data
  SetLength(data,actualRecordLength);
  CheckError(niScope_Read(vi,@channel[1],5.0,ActualRecordLength,@data[1],@wfmInfo),vi);
  //shows first 1000 samples
  writeln('Pointer value:' ,vi);
  for i:=1 to 10 do writeln('sample[',i,'] = ',data[i]:4:2);
  //close Session
  if vi<>VI_NULL then niScope_close(vi)
end.

GUI application onButtonClick code

Code: [Select]

procedure TForm1.StartBtnClick(Sender: TObject);
var
  resourceName:string;
  vi:ViSession;
  actualRecordLength:ViInt32;
  actualSampleRate:viReal64;
  data:array of viReal64;
  channel:string;
  wfmInfo:niScope_wfmInfo;
  procedure CheckError(AErrorCode: ViStatus; Avi: viSession);
var
  errorMessage:string;
begin
  SetLength(errorMessage,MAX_ERROR_DESCRIPTION);
  if (AErrorCode<>VI_SUCCESS) then begin
    niScope_GetErrorMessage(Avi,AErrorCode,Length(errorMessage),@errorMessage[1]);
    ShowMessage(errorMessage);
    if Avi<>VI_NULL then begin
       niScope_close(Avi);
    end;
    Halt;
  end;
 end;
begin
  //Setup hardware
  vi:=VI_NULL;
  resourceName:='Dev3';
  channel:='0';
  //Init Session
  CheckError(niScope_init(Pchar(@resourceName[1]),NISCOPE_VAL_FALSE,NISCOPE_VAL_FALSE,@vi),vi);
  //auto setup measurement
  CheckError(niScope_AutoSetup(vi),vi);

  CheckError(niScope_ActualRecordLength(vi,@actualRecordLength),vi);
   //read the actual record length and sample rate setuped by autosetup
  CheckError(niScope_ActualRecordLength(vi,@actualRecordLength),vi);
  CheckError(niScope_SampleRate(vi,@actualSampleRate),vi);
  //DataMemo.Append('Record lenght: '+IntToStr(actualRecordLength));
  //DataMemo.Append('Sample Rate: '+FloatToStrF(actualSampleRate,ffFixed,6,2));

  //set buffer length(array) and read data
  if  actualRecordLength >1 then begin
    SetLength(data,actualRecordLength);
    niScope_Read(vi,@channel[1],5.0,ActualRecordLength,@data[1],@wfmInfo);
    //shows first 1000 samples
    //for i:=1 to 1000 do DataMemo.Append('Sample['+IntToStr(i)+'] = '+FloatToStrF(data[i],ffFixed,4,2));
  end;

  //close Session
  if vi<>VI_NULL then niScope_close(vi)
end;                   


[mig-31]

Problem solved!

Thank guys, who found my stupid mistake with cdecl and stdcall convetion error!
There is first small worked example with autosetuped card.
To your own project simply add niscope and visatype to USES.

Code: [Select]

program test;

{$mode objfpc}{$H+}

uses
  {$IFDEF UNIX}{$IFDEF UseCThreads}
  cthreads,
  {$ENDIF}{$ENDIF}
  Classes, niscope, visatype,sysutils
  { you can add units after this };
var
  resourceName:string='Dev3';
  vi:ViSession=VI_NULL;
  wfmNum:ViInt32;
  actualRecordLength:dword;
  actualSampleRate:viReal64;
  data:array of viReal64;
  channel:string = '0';
  wfmInfo:array of niScope_wfmInfo;
  i:longint;
procedure CheckError(AErrorCode: ViStatus; Avi: viSession);
var
  errorMessage:string;
  bufferSize:ViStatus;
begin
  SetLength(errorMessage,MAX_ERROR_DESCRIPTION);
  if (AErrorCode<>VI_SUCCESS) then begin
    //should call twice because we don't know errorMessage length
    //get string length
    bufferSize:=niScope_GetErrorMessage(Avi,AErrorCode,0,@errorMessage[1]);
   //get Error message
    SetLength(errorMessage,bufferSize);
    niScope_GetErrorMessage(Avi,AErrorCode,Length(errorMessage),@errorMessage[1]);
    writeln(errorMessage);
    if Avi<>VI_NULL then begin
       niScope_close(Avi);
    end;
    Halt;
  end;
 end;
begin
  //Init Session
  CheckError(niScope_init(PChar(@resourceName[1]),NISCOPE_VAL_FALSE,NISCOPE_VAL_FALSE,@vi),vi);
  writeln('Vi handler value (should be 1):' ,vi);
  //auto setup measurement
  CheckError(niScope_AutoSetup(vi),vi);
  //read the actual record length and number of waveforms
  //setuped by autosetup
  CheckError(niScope_ActualRecordLength(vi,@actualRecordLength),vi);
  CheckError(niScope_SampleRate(vi,@actualSampleRate),vi);
  CheckError(niScope_ActualNumWfms(vi,PChar(@channel[1]),@wfmNum),vi);

  //set buffer for data (lenght of data array)
  SetLength(data,actualRecordLength*wfmNum);
  SetLength(wfmInfo,wfmNum);

  CheckError(niScope_Read(vi,PChar(@channel[1]),5.0,actualRecordLength,@data[0],@wfmInfo[0]),vi);
  //shows first 10 samples
  writeln('----first ten samples of record------------------');
  for i:=Low(data) to Low(data)+9 do writeln('sample[',i,'] = ',data[i]:4:2);
  //show Info
  writeln('---------------------------------------------------');
  writeln('Record lenght: ',actualRecordLength);
  writeln('Sample rate: ',actualSampleRate);
  writeln('Number of waveforms: ',wfmNum);
  //show Info from wfmInfo record
  writeln('Actual samples: ',wfmInfo[0].actualSamples);
  writeln('X Increament: ',wfmInfo[0].xIncrement);
  writeln('Gain: ',wfmInfo[0].Gain);
  //close Session
  if vi<>VI_NULL then niScope_close(vi)
end.                         
Find corrected bindings in the attachment

[mig-31]

There is next example based on binary acquisition example from NI-Scope driver.

[mig-31]

Hi,

there is corrected (bugs in visatype.pas missing of some pointers definitions) NI-Scope pascal bindings for NI-Scope 3.1 for Linux(to correct installation of NI-Scope install NIDAQmx 8.0.2 for Linux after NI-Scope).

Tested under Scientific Linux 6.4 on National Instruments PXI system:
1. NI PXIe-1078 chassic.
2. NI PXIe-8101 controller.
3. 2x NI PXI-5122 (NI-Scope 3.1 for Linux driver needed).

Autosetup code example

Code: [Select]

program test;

{$mode objfpc}{$H+}

uses
  {$IFDEF UNIX}{$IFDEF UseCThreads}
  cthreads,
  {$ENDIF}{$ENDIF}
  Classes, niscope, visatype,sysutils
  { you can add units after this };
var
  resourceName:string='Dev1';
  vi:ViSession=VI_NULL;
  wfmNum:ViInt32;
  actualRecordLength:dword;
  actualSampleRate:viReal64;
  data:array of viReal64;
  channel:string = '0';
  wfmInfo:array of niScope_wfmInfo;
  i:longint;
procedure CheckError(AErrorCode: ViStatus; Avi: viSession);
var
  errorMessage:string='';
  bufferSize:ViStatus;
begin
  SetLength(errorMessage,MAX_ERROR_DESCRIPTION);
  if (AErrorCode<>VI_SUCCESS) then begin
    //due on unkown string length niScope_GetErrorMessage should call twice
    //get buffer size
    bufferSize:=niScope_GetError(Avi,@AErrorCode,0,@errorMessage[1]);
    //read error message
    SetLength(errorMessage,bufferSize);
    niScope_GetError(Avi,@AErrorCode,Length(errorMessage),@errorMessage[1]);
    writeln(errorMessage);
    if Avi<>VI_NULL then begin
       niScope_close(Avi);
    end;
    Halt;
  end;
 end;
begin
  //Init Session
  CheckError(niScope_init(PChar(@resourceName[1]),NISCOPE_VAL_FALSE,NISCOPE_VAL_FALSE,@vi),vi);
  writeln('Vi handler value (should be 1):' ,vi);
  //auto setup measurement
  CheckError(niScope_AutoSetup(vi),vi);
  //read the actual record length and number of waveforms
  //setuped by autosetup
  CheckError(niScope_ActualRecordLength(vi,@actualRecordLength),vi);
  CheckError(niScope_SampleRate(vi,@actualSampleRate),vi);
  CheckError(niScope_ActualNumWfms(vi,PChar(@channel[1]),@wfmNum),vi);

  //set buffer for data (lenght of data array)
  SetLength(data,actualRecordLength*wfmNum);
  SetLength(wfmInfo,wfmNum);

  CheckError(niScope_Read(vi,PChar(@channel[1]),5.0,actualRecordLength,@data[0],@wfmInfo[0]),vi);
  //shows first 10 samples
  writeln('----first ten samples of record------------------');
  for i:=Low(data) to Low(data)+9 do writeln('sample[',i,'] = ',data[i]:4:2);
  //show Info
  writeln('---------------------------------------------------');
  writeln('Record lenght: ',actualRecordLength);
  writeln('Sample rate: ',actualSampleRate);
  writeln('Number of waveforms: ',wfmNum);
  //show Info from wfmInfo record
  writeln('Actual samples: ',wfmInfo[0].actualSamples);
  writeln('X Increament: ',wfmInfo[0].xIncrement);
  writeln('Gain: ',wfmInfo[0].Gain);
  //close Session
  if vi<>VI_NULL then niScope_close(vi)
end.

Binary acquisition example

Code: [Select]

program binaryacq;

{$mode objfpc}{$H+}

uses
  {$IFDEF UNIX}{$IFDEF UseCThreads}
  cthreads,
  {$ENDIF}{$ENDIF}
  Classes,niscope,visatype
  { you can add units after this };
 var
   error:ViStatus = VI_SUCCESS;
   vi:ViSession;
   //Variables setuped hardware
   resourceName:string = 'Dev1';
   channelName:string = '0,1';  //nastavit merici kanal
   verticalRange:ViReal64 = 10;//rozsah -5 - 5 V
   verticalOffset:ViReal64 = 0.0;
   minSampleRate:ViReal64 = 2e5;
   minRecordLength:ViInt32 = 1000;
   binaryDataType:ViInt32;
   numWaveform:ViInt32;
   actualRecordLength:ViInt32;
   //Default values
   triggerType:ViInt32 = 0; //Immediate trigger
   triggerCoupling:ViInt32 = NISCOPE_VAL_DC;
   triggerSlope:ViInt32 = NISCOPE_VAL_POSITIVE;
   triggerLevel:ViReal64 = 0.0;
   triggerHoldoff:ViReal64 = 0.0;
   triggerDelay:ViReal64 = 0.0;
   triggerSource:string = '0';//nastavit kanal pro trigger
   refPosition:ViReal64 = 50.0;
   timeout:ViReal64 = 5.0;
   stop:ViInt32;
   i,j:ViInt32;

   wfmInfo:array of niScope_wfmInfo;
   scaledWfm:array of ViReal64;
   //NI-5122 is 14-bit digitizer
   binaryWfm:array of ViInt16;
procedure CheckError(AErrorCode: ViStatus; Avi: viSession);
var
  errorMessage:string='';
  bufferSize:ViStatus;
begin
  SetLength(errorMessage,MAX_ERROR_DESCRIPTION);
  if (AErrorCode<>VI_SUCCESS) then begin
    //due on unkown string length niScope_GetErrorMessage should call twice
    //get buffer size
    bufferSize:=niScope_GetError(Avi,@AErrorCode,0,@errorMessage[1]);
    //read error message
    SetLength(errorMessage,bufferSize);
    niScope_GetError(Avi,@AErrorCode,Length(errorMessage),@errorMessage[1]);
    writeln(errorMessage);
    if Avi<>VI_NULL then begin
       niScope_close(Avi);
    end;
    Halt;
  end;
 end;
begin
   //Open the NI_SCOPE instrument handler
   CheckError(niScope_init(Pchar(@resourceName[1]),NISCOPE_VAL_FALSE,NISCOPE_VAL_FALSE,@vi),vi);

   //Configure the vertical parameters
   CheckError(niScope_ConfigureVertical(vi,PChar(@channelName[1]),verticalRange,verticalOffset,NISCOPE_VAL_DC,1.0,NISCOPE_VAL_TRUE),vi);
   //Configure the horizontal parameters
   //one record

   CheckError(niScope_ConfigureHorizontalTiming(vi,minSampleRate,minRecordLength,refPosition,1,VI_TRUE),vi);
   //Configure the trigger

   if triggerType<>0  //Edge
     then CheckError(niScope_ConfigureTriggerEdge(vi,PChar(@triggerSource[1]),triggerLevel,triggerSlope,triggerCoupling,triggerHoldoff,triggerDelay),vi)
     else CheckError(niScope_ConfigureTriggerImmediate(vi),vi);

   //Get number of waveforms
   CheckError(niScope_ActualNumWfms(vi,PChar(@channelName[1]),@numWaveform),vi);

   //Get record length
   CheckError(niScope_ActualRecordLength(vi,@ActualRecordLength),vi);
   writeln('Record length: ',ActualRecordLength);

   //Set buffer for data and waveform Info
   SetLength(binaryWfm,ActualRecordLength*numWaveform);
   SetLength(scaledWfm,ActualRecordLength*numWaveform);
   SetLength(wfmInfo,numWaveform);

   //signal acquisition  1 record
   stop:=NISCOPE_VAL_FALSE;
   while stop<>NISCOPE_VAL_TRUE do begin
     CheckError(niScope_InitiateAcquisition(vi),vi);
     CheckError(niScope_FetchBinary16(vi,PChar(@channelName[1]),timeout,actualRecordLength,@binaryWfm[0],@wfmInfo[0]),vi);
     stop:=NISCOPE_VAL_TRUE;
   end;
   niScope_Close(vi);
   //calculate scaled data from binary data
   for i:=0 to NumWaveform-1 do
     for j:=0 to ActualRecordLength-1 do scaledWfm[j+(i*ActualRecordLength-1)]:=binaryWfm[j+(i*ActualRecordLength-1)]*wfmInfo[i].Gain+wfmInfo[i].offset;

   for i:=0 to NumWaveform-1 do begin
     writeln('   Waveform channel   ',i+1);
     writeln('   First 10 samples ');
     writeln('----------------------');
     for j:=0 to 10 do writeln('value[',j,'] = ',scaledWfm[j+(i*ActualRecordLength-1)]:4:2);
     writeln('----------------------');
  end;
   writeln('program stoped');
end.                                       


[mig-31]

Hi, guys

I have created the wiki page for NI-Scope Pascal bindings http://wiki.freepascal.org/NI-Scope_examples.

I hope it would be usefull for others.

I invite you to check, improve, correct and add information.

Thanks.