NI-DAQmx and NI-DAQmx Base examples
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INTRODUCTION
National Instruments produce a wide range of DAQ cards, which are generally used for acquiring and generating signals.
These cards usually have a few analog inputs/outputs, digital inputs/outputs, counters and a frequency generator with hardware/software timing. Exact features (type, number, parameters) depends on the card type.
NIDAQmxBase.pas and NIDAQmx.pas are provided pascal bindings to National Instruments libraries and enable control of NI DAQ cards from programs written in Free Pascal.
What National Instruments Hardware is supported
Supported hardware list by NI-DAQmx and NI-DAQ Driver for different operating systems.
NI-DAQmxBase library
NI-DAQmxBase library or driver is multiplatform library for Windows (Windows XP 32 bit, Windows 7 32/64 bit, Windows Vista 32/64 bit, Windows 8 32/64 bit), macOS 32/64 bit and Linux 32/64 bit (SUSE, Scientific Linux, RedHat, CentOS), but doesn't implement all device features. For example, digital input/output ports speed is limited by computer speed ~100kHz, because DMA data transfer is not supported.
Download library from here. Read readme file to find the list of supported hardware and hardware features.
Latest Linux version 15.0 supports 64-bit OS, but you still need to install some 32-bit library.
LIST OF LIBRARIES:
compat-libstdc++.i686
expat.i686
glibc.i686
glibc-devel.i686
libdrm.i686
libgcc.i686
libselinux.i686
libstdc++.i686
libX11.i686
libXau.i686
libxcb.i686
libXdamage.i686
libXext.i686
libXinerama.i686
libXfixes.i686
libXxf86vm.i686
mesa-dri-drivers.i686
mesa-libGL.i686
nss-softokn-freebl.i686
zlib.i686
NI-DAQmx library
The NI-DAQmx library is only available for Windows 7 (SP1) 32/64 bit, Windows 8.1 32/64 bit, Windows 10 32/64 bit, Windows Embedded Standard 7 (SP1), Windows Server 2008 R2 (SP1) 32/64 bit). Download here)
Read readme file to find the list of supported hardware and hardware features.
HOW TO IDENTIFY PRESENT HARDWARE
To get list of devices present in your system Under Linux operation system use
1) nilsdev utility with NIDAQmx driver installed, 2) lsdaq utility with NIDAQmxBase driver installed.
Under Windows use NIMAX utility to get device list or set device alias etc.
Library documentation
You can find description of functions and properties in NI-DAQmx and NI-DAQmx Base C reference Help:
PASCAL bindings
Your can download pascal bindings nidaqmxbase.pas and nidaqmx.pas in this forum thread [1] or as a part of the LazMer project.
FUNCTION CALLING
Generally, when you need to acquire or gerenate data, call functions from nidaqmx.pas as follow
1. Create task: DAQmxCreateTask
2. Channel create:
a)DAQmxCreateDIChan/DAQmxCreateDOChan (digital input(s)/output(s))
b)DAQmxCreateAIVoltageChan/DAQmxCreateAOVoltageChan (analog input(s)/output(s))
3. Set timing if you need hardware timimg: DAQmxCfgSamplClkTiming
4. Start task: DAQmxStartTask
5. Read or write data from/to channel:
a)read data from digital port: DAQmxReadDigitalU8(8-bit port),DAQmxReadDigitalU32 (32-bit port),
b)write data to digital port: DAQmxWriteDigitalU8(8-bit port),DAQmxWriteDigitalU32 (32-bit port),
c)read data from analog input(s): DAQmxReadAnalogF64,
d)write data to analog output(s): DAQmxWriteAnalogF64.
6. Do job
7. End of program - stop and clear task: DAQmxStopTask and DAQmxClearTask
For error handling create function like ErrorCheck.
from nidaqmxbase.pas as follow
1. Create task: DAQmxBaseCreateTask
2. Channel create:
a)DAQmxBaseCreateDIChan/DAQmxBaseCreateDOChan (digital input(s)/output(s))
b)DAQmxBaseCreateAIVoltageChan/DAQmxBaseCreateAOVoltageChan (analog input(s)/output(s))
3. Set timing if you need hardware timimg: DAQmxBaseCfgSamplClkTiming
4. Start task: DAQmxBaseStartTask
5. Read or write data from/to channel:
a)read data from digital port: DAQmxBaseReadDigitalU8(8-bit port),DAQmxBaseReadDigitalU32 (32-bit port),
b)write data to digital port: DAQmxBaseWriteDigitalU8(8-bit port),DAQmxBaseWriteDigitalU32 (32-bit port),
c)read data from analog input(s): DAQmxBaseReadAnalogF64,
d)write data to analog output(s): DAQmxBaseWriteAnalogF64.
6. Do job
7. End of program - stop and clear task: DAQmxBaseStopTask and DAQmxBaseClearTask
For error handling create function like ErrorCheck.
Probably, some examples need to add @ before variable, which use as function parameter!!!
NI-DAQmx examples
DEVICE INFO
Get device list
You can check device list names using NI MAX program under Windows or nilsdev utility under Linux.
program devicelist;
{$mode objfpc}{$H+}
uses
{$IFDEF UNIX}{$IFDEF UseCThreads}
cthreads,
{$ENDIF}{$ENDIF}
Classes,nidaqmx,SysUtils
{ you can add units after this };
var
devicenames:array of Char;
infostr:string;
DeviceNamesList:TStringList;
buffersize:longint;
product_type:array of char;
devserialnum,is_simulated:longint;
is_simulated_str:string;
i:byte;
begin
DeviceNamesList:=TStringList.Create;
try
{**************************************************************************
Get device names present in the system
**************************************************************************}
//get buffer size or length of string of device list
buffersize:=DAQmxGetSystemInfoAttribute(DAQmx_Sys_DevNames,devicenames[0],[0]);
//set array of Char lenght
if Buffersize<>0 then begin
writeln('-------------------------------------------------------------');
writeln('|Device name | Product Type | # Serial number | Is Simulated?');
writeln('-------------------------------------------------------------');
SetLength(devicenames,buffersize);
//get the device list
DAQmxGetSystemInfoAttribute(DAQmx_Sys_DevNames,devicenames[0],[buffersize]);
//convert it to string: names are separated by comma
SetString(infostr,PChar(@devicenames[0]),buffersize);
//add names to TStringList
DeviceNamesList.CommaText:=infostr;
{************************************************************************
Get Product info
***********************************************************************}
for i:=0 to DeviceNamesList.Count-1 do begin
//get buffer size or length of string of product type
buffersize:=DAQmxGetDeviceAttribute(@DeviceNamesList.Strings[i][1],DAQmx_Dev_ProductType,Nil);
//set lenght of array of char
SetLength(product_type,buffersize);
//get product type info
DAQmxGetDeviceAttribute(@DeviceNamesList.Strings[i][1],DAQmx_Dev_ProductType,product_type[0],[buffersize]);
{***********************************************************************
Get Serial Number
**********************************************************************}
DAQmxGetDeviceAttribute(@DeviceNamesList.Strings[i][1],DAQmx_Dev_SerialNum,devserialnum,[1]);
//DeviceInfoGrid.Cells[3,i+1]:=IntToHex(devserialnum,8);
{***********************************************************************
Is simulated?
***********************************************************************}
DAQmxGetDeviceAttribute(@DeviceNamesList.Strings[i][1],DAQmx_Dev_IsSimulated,is_simulated,[1]);
if is_simulated = 0 then is_simulated_str:='No'
else is_simulated_str:='Yes';
//Show info
writeln('| ',DeviceNamesList.Strings[i],' | ',PChar(@product_type[0]),' | $',IntToHex(devserialnum,8),' |',is_simulated_str);
end;
end
else writeln('any device found');
finally
DeviceNamesList.Free;
end;
end.
Output example
-------------------------------------------------------------
|Device name | Product Type | # Serial number | Is Simulated?
-------------------------------------------------------------
| Dev1 | PCI-6250 | $018D0B90 |No
Get channel names
program chaninfo;
{$mode objfpc}{$H+}
uses
{$IFDEF UNIX}{$IFDEF UseCThreads}
cthreads,
{$ENDIF}{$ENDIF}
Classes,nidaqmx
{ you can add units after this };
var
buffersize,infotype:longint;
channelnames:array of char;
MsgChannelNames:array [0..255] of char;
MsgNoChannelsText:array [0..255] of char;
channeltype:byte;
DeviceName:string;
begin
{**********INPUT Device name and interested channel type **********************
**********WITHOUT CHEKING IF DEVICE EXITS IN THE SYSTEM**********************}
write('Enter device name, for example Dev1, Dev2 etc.: ');
readln(Devicename);
writeln('0 - analog inputs');
writeln('1 - analog outputs');
writeln('2 - digital inputs');
writeln('3 - digital outputs');
writeln('4 - counter inputs');
writeln('5 - counter outputs');
write('choose the number of required channel type:');
readln(channeltype);
{**********CHANNEL TYPE CHOSEN**********************************************}
case channeltype of
{********************ANALOG INPUTS NAMES*************************************}
0: begin
infotype:=DAQmx_Dev_AI_PhysicalChans;
MsgChannelNames:='Analog input names';
MsgNoChannelsText:='There are no analog inputs';
end;
{********************ANALOG OUTPUTS NAMES************************************}
1: begin
infotype:=DAQmx_Dev_AO_PhysicalChans;
MsgChannelNames:='Analog output names';
MsgNoChannelsText:='There are no analog outputs';
end;
{********************DIGITAL INPUT PORTS NAMES*******************************}
2: begin
infotype:=DAQmx_Dev_DI_Ports;
MsgChannelNames:='Digital input ports';
MsgNoChannelsText:='There are no digital input ports';
end;
{********************DIGITAL OUTPUT PORTS NAMES******************************}
3:begin
infotype:=DAQmx_Dev_DO_Ports;
MsgChannelNames:='Digital output ports';
MsgNoChannelsText:='There are no digital output ports';
end;
{********************COUNTER INPUT NAMES******************************}
4:begin
infotype:= DAQmx_Dev_CI_PhysicalChans;
MsgChannelNames:='Digital counter inputs';
MsgNoChannelsText:='There are no counter inputs ';
end;
{********************COUNTER OUTPUT NAMES******************************}
5:begin
infotype:= DAQmx_Dev_CO_PhysicalChans;
MsgChannelNames:='Digital counter outputs';
MsgNoChannelsText:='There are no counter outputs ';
end;
end;
{************GET CHANNEL NAMES*********************************************}
if (channeltype>=0) and (channeltype<6) then begin
//get buffer size or length of channelnames
buffersize:=DAQmxGetDeviceAttribute(@DeviceName[1],infotype,Nil);
if buffersize<>0 then begin
SetLength(channelnames,buffersize);
//get analog channel names separated by comma
DAQmxGetDeviceAttribute(@DeviceName[1],infotype,channelnames[0],[buffersize]);
//show info
writeln(MsgChannelNames+': '+PChar(@channelnames[0]));
end
else writeln(MsgNoChannelsText);
end;
end.
Output example
Enter device name, for example Dev1, Dev2 etc.: Dev1
0 - analog inputs
1 - analog outputs
2 - digital inputs
3 - digital outputs
4 - counter inputs
5 - counter outputs
choose the number of required channel type:0
Analog input names: Dev1/ai0, Dev1/ai1, Dev1/ai2, Dev1/ai3, Dev1/ai4, Dev1/ai5, Dev1/ai6, Dev1/ai7, Dev1/ai8, Dev1/ai9, Dev1/ai10, Dev1/ai11, Dev1/ai12, Dev1/ai13, Dev1/ai14, Dev1/ai15
ANALOG INPUTS/OUTPUTS
Acquire finite number of samples from one analog input
program aichan;
{$mode objfpc}{$H+}
uses
{$IFDEF UNIX}{$IFDEF UseCThreads}
cthreads,
{$ENDIF}{$ENDIF}
Classes, nidaqmx
{ you can add units after this };
var
AITaskHandle:TaskHandle;
data:array[1..1000] of double;
reads,i:longint;
{************Error handling procedure *****************************************
Example:
ErrorCheck(DAQmxCreateAIVoltageChan(AITaskHandle,'Dev1/ai0','',DAQmx_Val_RSE,-10.0,10.0,DAQmx_Val_Volts,NIL),AITaskHandle);
*******************************************************************************}
procedure ErrorCheck(AError:longint;ATaskHandle:longint);
var
errBuffer:array[0..2048] of char;
begin
//get error description
if Aerror<>0 then begin
DAQmxGetExtendedErrorInfo(@ErrBuffer[0],2048);
writeln(PChar(@ErrBuffer[0]));
//stop and cleat task
if Assigned(@ATaskHandle) then begin
DAQmxStopTask(ATaskHandle);
DAQmxClearTask(ATaskHandle);
end;
//stop program
Halt;
end;
end;
{*********************MAIN PROGRAM*********************************************
******************* without error handling************************************}
begin
//create task
DAQmxCreateTask('',@AITaskHandle);
//create analog input channel Dev1/ai0 (activate it)
//voltage range -10 - 10
DAQmxCreateAIVoltageChan(AITaskHandle,'Dev1/ai0','',DAQmx_Val_RSE,-10.0,10.0,DAQmx_Val_Volts,NIL);
//set timing
//Sample rate = 10000 (10 kHz), sample per channel =1000
//acquire finite samples (1000 samples) defined by DAQmx_Val_FiniteSamps
DAQmxCfgSampClkTiming(AITaskHandle,'OnboardClock',10000.0,DAQmx_Val_Rising,DAQmx_Val_FiniteSamps,1000);
//start task
DAQmxStartTask(AITaskHandle);
//acquire 1000 samples
DAQmxReadAnalogF64(AITaskHandle,1000,10.0,DAQmx_Val_GroupByChannel,@data[1],1000,@reads,NIL);
//show first 10 samples
writeln(reads,' samples were acquired');
writeln('');
writeln('Value of first 10 samples');
for i:=1 to 10 do writeln('sample[',i,'] = ',data[i]:4:2,' V');
//stop and clear task
DAQmxStopTask(AITaskHandle);
DAQmxClearTask(AITaskHandle);
end.
Output example
1000 samples were acquired
Value of first 10 samples
sample[1] = 0.23 V
sample[2] = 0.23 V
sample[3] = 0.23 V
sample[4] = 0.23 V
sample[5] = 0.23 V
sample[6] = 0.23 V
sample[7] = 0.23 V
sample[8] = 0.23 V
sample[9] = 0.23 V
sample[10] = 0.23 V
Continuously acquire samples from three analog inputs
program multiaichannel;
{$mode objfpc}{$H+}
uses
{$IFDEF UNIX}{$IFDEF UseCThreads}
cthreads,
{$ENDIF}{$ENDIF}
Classes, nidaqmx,crt
{ you can add units after this };
var
AITaskHandle:TaskHandle;
data:array of double;
reads:longint;
totalsamplereads:longint=0;
i:longint;
{************Error handling procedure *****************************************
Example:
ErrorCheck(DAQmxCreateAIVoltageChan(AITaskHandle,'Dev1/ai0','',DAQmx_Val_RSE,-10.0,10.0,DAQmx_Val_Volts,NIL),AITaskHandle);
*******************************************************************************}
procedure ErrorCheck(AError:longint;ATaskHandle:longint);
var
errBuffer:array[0..2048] of char;
begin
//get error description
if Aerror<>0 then begin
DAQmxGetExtendedErrorInfo(@ErrBuffer[0],2048);
writeln(PChar(@ErrBuffer[0]));
//stop and cleat task
if Assigned(@ATaskHandle) then begin
DAQmxStopTask(ATaskHandle);
DAQmxClearTask(ATaskHandle);
end;
//stop program
Halt;
end;
end;
{*********************MAIN PROGRAM*********************************************
******************* without error handling************************************}
begin
//Set buffer size for data acquiring, sample per channel 1000
//buffer size(data -array variable) = 3 channel * 1000 samples per channel
Setlength(data,3*1000);
//create task
DAQmxCreateTask('',@AITaskHandle);
//create analog input channel Dev1/ai0:2 (activate 3 channels)
//voltage range -10 - 10
DAQmxCreateAIVoltageChan(AITaskHandle,'Dev1/ai0:2','',DAQmx_Val_RSE,-10.0,10.0,DAQmx_Val_Volts,NIL);
//set timing
//Sample rate = 10000 (10 kHz), sample per channel =1000
//acquire finite samples (1000 samples) defined by DAQmx_Val_Cont_Samps
DAQmxCfgSampClkTiming(AITaskHandle,'OnboardClock',10000.0,DAQmx_Val_Rising,DAQmx_Val_ContSamps,1000);
//start task
DAQmxStartTask(AITaskHandle);
//acquire 10000 samples for each channel
while totalsamplereads<10000 do begin
//1000- sample rate, 3000 - buffer size(data -array variable) = 3 channel * 1000 samples per channel
DAQmxReadAnalogF64(AITaskHandle,1000,10.0,DAQmx_Val_GroupByChannel,@data[0],3000,@reads,NIL);
totalsamplereads:=totalsamplereads+reads;
writeln('aquired number of samples: ',totalsamplereads);
end;
//show first 10 samples from last 1000 samples acquired from each channel
writeln('');
writeln('Value of first 10 samples of last 1000 samples for each channel');
writeln('| chan0 | chan1 | chan2 | ');
for i:= 0 to 9 do writeln('|',data[i]:5:2,' V| ',data[i+1000]:5:2,' V| ',data[i+2000]:5:2,' V|');
//stop and clear task
DAQmxStopTask(AITaskHandle);
DAQmxClearTask(AITaskHandle);
end.
Output example
acquired number of samples: 1000
aquired number of samples: 2000
acquired number of samples: 3000
acquired number of samples: 4000
acquired number of samples: 5000
acquired number of samples: 6000
acquired number of samples: 7000
acquired number of samples: 8000
acquired number of samples: 9000
acquired number of samples: 10000
Value of first 10 samples of last 1000 samples for each channel
| chan0 | chan1 | chan2 |
| 5.07 V| 5.07 V| 5.06 V|
| 5.07 V| 5.07 V| 5.06 V|
| 5.07 V| 5.06 V| 5.07 V|
| 5.06 V| 5.06 V| 5.07 V|
| 5.06 V| 5.07 V| 5.07 V|
| 5.07 V| 5.07 V| 5.06 V|
| 5.07 V| 5.07 V| 5.07 V|
| 5.06 V| 5.06 V| 5.07 V|
| 5.06 V| 5.06 V| 5.06 V|
| 5.07 V| 5.07 V| 5.06 V|
Start acquisition on analog input by digital trigger
This example demonstrates how to start acquisition by digital trigger.
program aidigtrig;
{$mode objfpc}{$H+}
uses
{$IFDEF UNIX}{$IFDEF UseCThreads}
cthreads,
{$ENDIF}{$ENDIF}
Classes,nidaqmx,crt
{ you can add units after this };
var
AITaskHandle:TaskHandle;
channel:string = 'Dev1/ai0';
SampleRate:double = 10000;
SamplePerChannel:longint = 1000;
PretriggerSamples: longint= 100; //MUST be > 2
reads:longint = 0;
i:longint;
data:array of double;
procedure ErrorCheck(AError:longint;ATaskHandle:longint);
var
errBuffer:array[0..2048] of char;
begin
//get error description
if Aerror<>0 then begin
DAQmxGetExtendedErrorInfo(@ErrBuffer[0],2048);
writeln(ErrBuffer);
//stop and cleat task
if Assigned(@ATaskHandle) then begin
DAQmxStopTask(ATaskHandle);
DAQmxClearTask(ATaskHandle);
end;
//stop acquisition
writeln('Program stoped');
Halt;
end;
end;
begin
//set buffer length
SetLength(data,SamplePerChannel);
//create take
DAQmxCreateTask('',@AITaskHandle);
//create ai channel
ErrorCheck(DAQmxCreateAIVoltageChan(AITaskHandle,@channel[1],'',DAQmx_Val_RSE,-10.0,10.0,DAQmx_Val_Volts,Nil),AITaskHandle);
//configure sample clock
ErrorCheck(DAQmxCfgSampClkTiming(AITaskHandle,'',SampleRate,DAQmx_Val_Rising,DAQmx_Val_FiniteSamps,SamplePerChannel),AITaskHandle);
//configure triger with 100 pretriggered samples
ErrorCheck(DAQmxCfgDigEdgeRefTrig(AITaskHandle,'/Dev1/PFI0',DAQmx_Val_Rising,PretriggerSamples),AITaskHandle);
//start task
ErrorCheck(DAQmxStartTask(AITaskHandle),AITaskHandle);
//acquire data
writeln('Press any key to stop acquisition');
i := 0;
repeat
ErrorCheck(DAQmxReadAnalogF64(AITaskHandle,SamplePerChannel,10.0,DAQmx_Val_GroupByChannel,@data[0],Length(data),@reads,Nil),AITaskHandle);
i := i + reads;
writeln('Number of acquired samples: ', i);
until keypressed;
//show last readed number of samples
for i:=Low(data) to High(data) do writeln('data[',i,'] = ', data[i]:4:2);
//stop and clear task
if Assigned(@AITaskHandle) then begin
DAQmxStopTask(AITaskHandle);
DAQmxClearTask(AITaskHandle);
end;
end.
Analog output software controlled
This example demonstrates sinusoidal waveform generation with software timed control analog output.
program aochansw;
{$mode objfpc}{$H+}
uses
{$IFDEF UNIX}{$IFDEF UseCThreads}
cthreads,
{$ENDIF}{$ENDIF}
Classes,Crt,SysUtils,nidaqmx
{ you can add units after this };
var
AOTaskHandle:TaskHandle;
//data writted to analog output
data:array [0..999] of double;
writtensamples:integer;
i:integer;
{************Error handling procedure *****************************************
Example:
ErrorCheck(DAQmxCreateAIVoltageChan(AITaskHandle,'Dev1/ai0','',DAQmx_Val_RSE,-10.0,10.0,DAQmx_Val_Volts,NIL),AITaskHandle);
*******************************************************************************}
procedure ErrorCheck(AError:longint;ATaskHandle:longint);
var
errBuffer:array[0..2048] of char;
begin
//get error description
if Aerror<>0 then begin
DAQmxGetExtendedErrorInfo(@ErrBuffer[0],2048);
writeln(PChar(@ErrBuffer[0]));
//stop and cleat task
if Assigned(@ATaskHandle) then begin
DAQmxStopTask(ATaskHandle);
DAQmxClearTask(ATaskHandle);
end;
//stop program
Halt;
end;
end;
begin
//prepare data for analog output
//sin waveform
for i:=Low(data) to High(data) do data[i]:=9.95*sin(i*2.0*Pi/1000.0);
//create task
DAQmxCreateTask('',@AOTaskHandle);
//configure analog output channel
ErrorCheck(DAQmxCreateAOVoltageChan(AOTaskHandle,'Dev1/ao0','',-10.0,10.0,DAQmx_Val_Volts,Nil),AOTaskHandle);
//start task
ErrorCheck(DAQmxStartTask(AOTaskHandle),AOTaskHandle);
writeln('Press any key to stop generation');
//continuosly waveform generation
//if you call task start function (DAQmxStartTask)
//before output write function (for example DAQmxWriteAnalogScalarF64)
//set AutoStart parameter to 1
//if output function berofe start AutoStart = 0
i:=0;
repeat
sleep(1);
ErrorCheck(DAQmxWriteAnalogScalarF64(AOTaskHandle,1,10.0,data[i],Nil),AOTaskHandle);
inc(i);
if i >=1000 then i:=0;
until keypressed;
//stop and clear task
if Assigned(@AOTaskHandle) then begin
DAQmxStopTask(AOTaskHandle);
DAQmxClearTask(AOTaskHandle);
end;
end.
Analog output hardware controlled
This example demonstrates how to generate finite number of samples on analog output channel.
program aochannel;
{$mode objfpc}{$H+}
uses
{$IFDEF UNIX}{$IFDEF UseCThreads}
cthreads,
{$ENDIF}{$ENDIF}
Classes,nidaqmx
{ you can add units after this };
var
AOTaskHandle:TaskHandle;
//data writted to analog output
data:array [0..3999] of double;
writtensamples:integer;
i:integer;
{************Error handling procedure *****************************************
Example:
ErrorCheck(DAQmxCreateAIVoltageChan(AITaskHandle,'Dev1/ai0','',DAQmx_Val_RSE,-10.0,10.0,DAQmx_Val_Volts,NIL),AITaskHandle);
*******************************************************************************}
procedure ErrorCheck(AError:longint;ATaskHandle:longint);
var
errBuffer:array[0..2048] of char;
begin
//get error description
if Aerror<>0 then begin
DAQmxGetExtendedErrorInfo(@ErrBuffer[0],2048);
writeln(PChar(@ErrBuffer[0]));
//stop and cleat task
if Assigned(@ATaskHandle) then begin
DAQmxStopTask(ATaskHandle);
DAQmxClearTask(ATaskHandle);
end;
//stop program
Halt;
end;
end;
{*********************MAIN PROGRAM*********************************************
}
begin
//prepare data for analog output
for i:=Low(data) to High(data) do data[i]:= 5.0*i/4000.0;
//create task
DAQmxCreateTask('',@AOTaskHandle);
//configure analog output channel
ErrorCheck(DAQmxCreateAOVoltageChan(AOTaskHandle,'Dev1/ao0','',-10.0,10.0,DAQmx_Val_Volts,Nil),AOTaskHandle);
//configure clock
ErrorCheck(DAQmxCfgSampClkTiming(AOTaskHandle,'',1000.0,DAQmx_Val_Rising,DAQmx_Val_FiniteSamps,4000),AOTaskHandle);
//write data to buffer
ErrorCheck(DAQmxWriteAnalogF64(AOTaskHandle,4000,0,10.0,DAQmx_Val_GroupByChannel,data,@writtensamples,Nil),AOTaskHandle);
//start task
ErrorCheck(DAQmxStartTask(AOTaskHandle),AOTaskHandle);
//wait until all samples are generated
ErrorCheck(DAQmxWaitUntilTaskDone(AOTaskHandle,10.0),AOTaskHandle);
//stop and clear task
if Assigned(@AOTaskHandle) then begin
DAQmxStopTask(AOTaskHandle);
DAQmxClearTask(AOTaskHandle);
end;
end.
DIGITAL INPUTS/OUTPUTS
Most of DAQ cards have two types of digital ports (input/output): correlated and static. Static ports are software timed, correlated are software or hardware timed by the external or internal clock for example couter output signal (/Dev1/Ctr0InternalOutput - couter0 as clock ). Check the documention to find it, for example NI-PCI6250 have three 8-bit ports: port0 - correlated, port1,port2 - static; NI-PCI6224 two ports: 32-bit port0 - correlated, 8-bit port1 - static.
Read/Write data from/to 8-bit and 32-bit digital port use an appropriate function DAQmxReadDigitalU8, DAQmxWriteDigitalU8 and DAQmxReadDigitalU32, DAQmxWriteDigitalU32.
Different behaviour of collerated port0, when it sets as input, occured under Linux and Windows: software timed works only under Windows, with external clock works under Windows and Linux!!!
Software timed digital input
To check it, connected +5V(depend on hardware) to one of available port pins.
program diport;
{$mode objfpc}{$H+}
uses
{$IFDEF UNIX}{$IFDEF UseCThreads}
cthreads,
{$ENDIF}{$ENDIF}
Classes,nidaqmx,SysUtils,StrUtils
{ you can add units after this };
var
DITaskHandle:TaskHandle;
data:array [0..9] of byte;
reads:longint = 0;
totalreads:longint = 0;
i:longint ;
{************Error handling procedure *****************************************
Example:
ErrorCheck(DAQmxCreateAIVoltageChan(AITaskHandle,'Dev1/ai0','',DAQmx_Val_RSE,-10.0,10.0,DAQmx_Val_Volts,NIL),AITaskHandle);
*******************************************************************************}
procedure ErrorCheck(AError:longint;ATaskHandle:longint);
var
errBuffer:array[0..2048] of char;
begin
//get error description
if Aerror<>0 then begin
DAQmxGetExtendedErrorInfo(@ErrBuffer[0],2048);
writeln(PChar(@ErrBuffer[0]));
//stop and cleat task
if Assigned(@ATaskHandle) then begin
DAQmxStopTask(ATaskHandle);
DAQmxClearTask(ATaskHandle);
end;
//stop program
Halt;
end;
end;
{*******************MAIN PROGRAM WITH ERROR HANDLING*************************}
begin
//task create
ErrorCheck(DAQmxCreateTask('',@DITaskHandle),DITaskHandle);
//digital input port create
ErrorCheck(DAQmxCreateDIChan(DITaskHandle,'Dev1/port1','',DAQmx_Val_ChanForAllLines),DITaskHandle);
//Start Task
ErrorCheck(DAQmxStartTask(DITaskHandle),DITaskHandle);
//read 10 samples from 8-bit digital port (for example NI PCI-6250 card port1(pins P1.0-P1.7))
//for 32-bit digital port use DAQmxReadDigitalU32 function
ErrorCheck(DAQmxReadDigitalU8(DITaskHandle,10,10.0,DAQmx_Val_GroupByChannel,@data,10,@reads,Nil),DITaskHandle);
writeln('number of readed samples: ',reads);
for i:=0 to 9 do writeln('data [',i,'] = %',IntToBin(data[i],8));
//stop and clear task
if DITaskHandle<>0 then begin
DAQmxStopTask(DITaskHandle);
DAQmxClearTask(DITaskHandle);
end;
end.
Output example: +5V connected to pin P1.2 port1 on NI-PCI6250 card.
number of readed samples: 10
data [0] = %00000100
data [1] = %00000100
data [2] = %00000100
data [3] = %00000100
data [4] = %00000100
data [5] = %00000100
data [6] = %00000100
data [7] = %00000100
data [8] = %00000100
data [9] = %00000100
Hardware timed digital input
This example shows using of counter output signal as a clock for digital inputs port for hardware timed acquire data on digital inputs. This feature is supported only for correlated digital port. In this example 8-bit port0 on NI-PCI6250 card is used to check this function.
To check it, connected +5V(depend on hardware) to one of available pins on correlated digital port.
program diporttimed;
{$mode objfpc}{$H+}
uses
{$IFDEF UNIX}{$IFDEF UseCThreads}
cthreads,
{$ENDIF}{$ENDIF}
Classes,nidaqmx,SysUtils,StrUtils
{ you can add units after this };
var
DITaskHandle,CtrTaskHandle:TaskHandle;
data:array [0..9] of byte;
reads:longint = 0;
totalreads:longint = 0;
i:longint ;
{************Error handling procedure *****************************************
Example:
ErrorCheck(DAQmxCreateAIVoltageChan(AITaskHandle,'Dev1/ai0','',DAQmx_Val_RSE,-10.0,10.0,DAQmx_Val_Volts,NIL),AITaskHandle);
*******************************************************************************}
procedure ErrorCheck(AError:longint;ATaskHandle:longint);
var
errBuffer:array[0..2048] of char;
begin
//get error description
if Aerror<>0 then begin
DAQmxGetExtendedErrorInfo(@ErrBuffer[0],2048);
writeln(PChar(@ErrBuffer[0]));
//stop and cleat task
if Assigned(@ATaskHandle) then begin
DAQmxStopTask(ATaskHandle);
DAQmxClearTask(ATaskHandle);
end;
//stop program
Halt;
end;
end;
{*******************MAIN PROGRAM WITH ERROR HANDLING*************************}
begin
{******CREATE COUNTER OUTPUT TO USE IT AS CLOCK FOR DIGITAL PORT INPUTS******
*******INTERNALLY CONNECTED ON M-SERIES as /Dev1/Ctr0InternalOutput**********}
//create couter task
ErrorCheck(DAQmxCreateTask('Counter Task',@CtrTaskHandle),CtrTaskHandle);
//create counter output channel
//Frequency 1000 Hz, duty 0.5
ErrorCheck(DAQmxCreateCOPulseChanFreq(CtrTaskHandle,'Dev1/ctr0','',DAQmx_Val_Hz,DAQmx_Val_Low,0,1000,0.5),CtrTaskHandle);
//timing 1000 samples per second
ErrorCheck(DAQmxCfgImplicitTiming(CtrTaskHandle,DAQmx_Val_ContSamps,1000),CtrTaskHandle);
//start counter task
ErrorCheck(DAQmxStartTask(CtrTaskHandle),CtrTaskHandle);
//digital input task create
ErrorCheck(DAQmxCreateTask('Digital input task',@DITaskHandle),DITaskHandle);
//digital input port create
ErrorCheck(DAQmxCreateDIChan(DITaskHandle,'Dev1/port0','',DAQmx_Val_ChanForAllLines),DITaskHandle);
//timing use counter output as clock source internally connected
//as /Dev1/Ctr0InternalOutput
ErrorCheck(DAQmxCfgSampClkTiming(DITaskHandle,'/Dev1/Ctr0InternalOutput',1000.0,DAQmx_Val_Rising,DAQmx_Val_FiniteSamps,1000),DITaskHandle);
//Start digital input Task
ErrorCheck(DAQmxStartTask(DITaskHandle),DITaskHandle);
//read 10 samples from 8-bit digital port for example correlated port0
//for 32-bit digital port use DAQmxReadDigitalU32 function
ErrorCheck(DAQmxReadDigitalU8(DITaskHandle,10,10.0,DAQmx_Val_GroupByChannel,@data,10,@reads,Nil),DITaskHandle);
writeln('number of readed samples: ',reads);
for i:=0 to 9 do writeln('data [',i,'] = %',IntToBin(data[i],8));
//stop and clear task
DAQmxStopTask(DITaskHandle);
DAQmxClearTask(DITaskHandle);
DAQmxStopTask(CtrTaskHandle);
DAQmxClearTask(CtrTaskHandle);
end.
Output example: +5V connected to pin P0.5 on port0 on NI-PCI6250 card.
number of readed samples: 10
data [0] = %00100000
data [1] = %00100000
data [2] = %00100000
data [3] = %00100000
data [4] = %00100000
data [5] = %00100000
data [6] = %00100000
data [7] = %00100000
data [8] = %00100000
data [9] = %00100000
Software controlled digital output
To check it connect digital output(s) to oscilloscope or to card analog input.
program doportlpi;
{$mode objfpc}{$H+}
uses
{$IFDEF UNIX}{$IFDEF UseCThreads}
cthreads,
{$ENDIF}{$ENDIF}
Classes,nidaqmx,SysUtils,StrUtils
{ you can add units after this };
var
DOTaskHandle:TaskHandle;
data: byte;
written:longint = 0;
{************Error handling procedure *****************************************
Example:
ErrorCheck(DAQmxCreateAIVoltageChan(AITaskHandle,'Dev0/ai0','',DAQmx_Val_RSE,-10.0,10.0,DAQmx_Val_Volts,NIL),AITaskHandle);
*******************************************************************************}
procedure ErrorCheck(AError:longint;ATaskHandle:longint);
var
errBuffer:array[0..2048] of char;
begin
//get error description
if Aerror<>0 then begin
DAQmxGetExtendedErrorInfo(@ErrBuffer[0],2048);
writeln(PChar(@ErrBuffer[0]));
//stop and cleat task
if Assigned(@ATaskHandle) then begin
DAQmxStopTask(ATaskHandle);
DAQmxClearTask(ATaskHandle);
end;
//stop program
Halt;
end;
end;
{*******************MAIN PROGRAM WITH ERROR HANDLING*************************}
begin
//task create
ErrorCheck(DAQmxCreateTask('',@DOTaskHandle),DOTaskHandle);
//digital input port create
ErrorCheck(DAQmxCreateDOChan(DOTaskHandle,'Dev1/port0','',DAQmx_Val_ChanForAllLines),DOTaskHandle);
//task start
//no need to start task
ErrorCheck(DAQmxStartTask(DOTaskHandle),DOTaskHandle);
//for 32-bit digital port use DAQmxReadDigitalU32 function
//set 1 on all lines of digital port
//change data:=0 to set 0 or use DAQmxResetDevice function to
data:=0;
ErrorCheck(DAQmxWriteDigitalU8(DOTaskHandle,1,1,10.0,DAQmx_Val_GroupByChannel,@data,@written,Nil),DOTaskHandle);
//use DAQmxResetDevice function here to set signal on Low state
writeln('number of written samples: ',written);
//stop and clear task
if DOTaskHandle<>0 then begin
DAQmxStopTask(DOTaskHandle);
DAQmxClearTask(DOTaskHandle);
end;
end.
Hardware timed digital outputs with counter output used as source clock
To check it connect digital output(s) to oscilloscope or to card analog input.
program doporttimed;
{$mode objfpc}{$H+}
uses
{$IFDEF UNIX}{$IFDEF UseCThreads}
cthreads,
{$ENDIF}{$ENDIF}
Classes,nidaqmx,SysUtils,StrUtils,Crt
{ you can add units after this };
var
DOTaskHandle,CtrTaskHandle:TaskHandle;
data:array[0..7] of byte = (1,2,4,8,16,32,64,128);
written:longint = 0;
{************Error handling procedure *****************************************
Example:
ErrorCheck(DAQmxCreateAIVoltageChan(AITaskHandle,'Dev0/ai0','',DAQmx_Val_RSE,-10.0,10.0,DAQmx_Val_Volts,NIL),AITaskHandle);
*******************************************************************************}
procedure ErrorCheck(AError:longint;ATaskHandle:longint);
var
errBuffer:array[0..2048] of char;
begin
//get error description
if Aerror<>0 then begin
DAQmxGetExtendedErrorInfo(@ErrBuffer[0],2048);
writeln(PChar(@ErrBuffer[0]));
//stop and cleat task
if Assigned(@ATaskHandle) then begin
DAQmxStopTask(ATaskHandle);
DAQmxClearTask(ATaskHandle);
end;
//stop program
Halt;
end;
end;
{*******************MAIN PROGRAM WITH ERROR HANDLING*************************}
begin
{******CREATE COUNTER OUTPUT TO USE IT AS CLOCK FOR DIGITAL PORT OUTPUTS******
*******INTERNALLY CONNECTED ON M-SERIES as /Dev1/Ctr0InternalOutput**********}
//create couter task
ErrorCheck(DAQmxCreateTask('Counter Task',@CtrTaskHandle),CtrTaskHandle);
//create counter output channel
//Frequency 1000 Hz, duty 0.5
ErrorCheck(DAQmxCreateCOPulseChanFreq(CtrTaskHandle,'Dev1/ctr0','',DAQmx_Val_Hz,DAQmx_Val_Low,0,10000,0.5),CtrTaskHandle);
//timing 1000 samples per second
ErrorCheck(DAQmxCfgImplicitTiming(CtrTaskHandle,DAQmx_Val_ContSamps,1000),CtrTaskHandle);
//start task
//start counter task
ErrorCheck(DAQmxStartTask(CtrTaskHandle),CtrTaskHandle);
//task create
ErrorCheck(DAQmxCreateTask('',@DOTaskHandle),DOTaskHandle);
//digital input port create
ErrorCheck(DAQmxCreateDOChan(DOTaskHandle,'Dev1/port0','',DAQmx_Val_ChanForAllLines),DOTaskHandle);
//timing
//frequency 1000Hz
ErrorCheck(DAQmxCfgSampClkTiming(DOTaskHandle,'/Dev1/Ctr0InternalOutput',1000.0,DAQmx_Val_Rising,DAQmx_Val_ContSamps,1000),DOTaskHandle);
//for 32-bit digital port use DAQmxWriteDigitalU32 function
//function sets to start task automaticly 3-rd parameter
//write 8 samples
ErrorCheck(DAQmxWriteDigitalU8(DOTaskHandle,8,1,10.0,DAQmx_Val_GroupByChannel,data,@written,Nil),DOTaskHandle);
writeln('number of written samples: ',written);
//stop and clear task
DAQmxStopTask(DOTaskHandle);
DAQmxClearTask(DOTaskHandle);
DAQmxStopTask(CtrTaskHandle);
DAQmxClearTask(CtrTaskHandle);
end.
COUNTER INPUTS/OUTPUTS
Pulse generation
This example demonstrates pwm generaton with frequency 1000Hz and duty circle 0.5.
program doporttimed;
{$mode objfpc}{$H+}
uses
{$IFDEF UNIX}{$IFDEF UseCThreads}
cthreads,
{$ENDIF}{$ENDIF}
Classes,nidaqmx,SysUtils,StrUtils,Crt
{ you can add units after this };
var
CtrTaskHandle:TaskHandle;
{************Error handling procedure *****************************************
Example:
ErrorCheck(DAQmxCreateAIVoltageChan(AITaskHandle,'Dev0/ai0','',DAQmx_Val_RSE,-10.0,10.0,DAQmx_Val_Volts,NIL),AITaskHandle);
*******************************************************************************}
procedure ErrorCheck(AError:longint;ATaskHandle:longint);
var
errBuffer:array[0..2048] of char;
begin
//get error description
if Aerror<>0 then begin
DAQmxGetExtendedErrorInfo(@ErrBuffer[0],2048);
writeln(PChar(@ErrBuffer[0]));
//stop and cleat task
if Assigned(@ATaskHandle) then begin
DAQmxStopTask(ATaskHandle);
DAQmxClearTask(ATaskHandle);
end;
//stop program
Halt;
end;
end;
{*******************MAIN PROGRAM WITH ERROR HANDLING*************************}
begin
//create couter task
ErrorCheck(DAQmxCreateTask('Counter Task',@CtrTaskHandle),CtrTaskHandle);
//create counter output channel
//Frequency 1000 Hz, duty 0.5
ErrorCheck(DAQmxCreateCOPulseChanFreq(CtrTaskHandle,'Dev1/ctr0','',DAQmx_Val_Hz,DAQmx_Val_Low,0,10000,0.5),CtrTaskHandle);
//timing 1000 samples per second
ErrorCheck(DAQmxCfgImplicitTiming(CtrTaskHandle,DAQmx_Val_ContSamps,1000),CtrTaskHandle);
//start task
ErrorCheck(DAQmxStartTask(CtrTaskHandle),CtrTaskHandle);
writeln('Press any key to stop generation');
repeat
until keypressed;
DAQmxStopTask(CtrTaskHandle);
DAQmxClearTask(CtrTaskHandle);
end.
Event counting
In this example first counter(Dev1/ctr0) is configurated as counter output for frequency generation, second (Dev1/ctr1) as counter input for pulse counting. First counter also used as clock source for second one.
program eventcounting;
{$mode objfpc}{$H+}
uses
{$IFDEF UNIX}{$IFDEF UseCThreads}
cthreads,
{$ENDIF}{$ENDIF}
Classes,nidaqmx,SysUtils,StrUtils,Crt
{ you can add units after this };
var
CtrOutTaskHandle,CtrInTaskHandle:TaskHandle;
reads:cardinal=0;
data:array [0..999] of longint;
i:longint;
{************Error handling procedure *****************************************
Example:
ErrorCheck(DAQmxCreateAIVoltageChan(AITaskHandle,'Dev0/ai0','',DAQmx_Val_RSE,-10.0,10.0,DAQmx_Val_Volts,NIL),AITaskHandle);
*******************************************************************************}
procedure ErrorCheck(AError:longint;ATaskHandle:longint);
var
errBuffer:array[0..2048] of char;
begin
//get error description
if Aerror<>0 then begin
DAQmxGetExtendedErrorInfo(@ErrBuffer[0],2048);
writeln(PChar(@ErrBuffer[0]));
//stop and cleat task
if Assigned(@ATaskHandle) then begin
DAQmxStopTask(ATaskHandle);
DAQmxClearTask(ATaskHandle);
end;
//stop program
Halt;
end;
end;
{*******************MAIN PROGRAM WITH ERROR HANDLING*************************}
begin
{****************CREATE COUNTER OUTPUT***************************************}
//create couter output task
ErrorCheck(DAQmxCreateTask('Counter output task',@CtrOutTaskHandle),CtrOutTaskHandle);
//create counter output channel
//Frequency 1000 Hz, duty 0.5
ErrorCheck(DAQmxCreateCOPulseChanFreq(CtrOutTaskHandle,'Dev1/ctr0','',DAQmx_Val_Hz,DAQmx_Val_Low,0,10000,0.5),CtrOutTaskHandle);
//timing 1000 samples per second
ErrorCheck(DAQmxCfgImplicitTiming(CtrOutTaskHandle,DAQmx_Val_ContSamps,1000),CtrOutTaskHandle);
//start counter output task
ErrorCheck(DAQmxStartTask(CtrOutTaskHandle),CtrOutTaskHandle);
{*****************CREATE COUNTER INPUT***************************************}
//create couter output task
ErrorCheck(DAQmxCreateTask('Counter input task',@CtrInTaskHandle),CtrInTaskHandle);
//create input counter for pulse counting
ErrorCheck(DAQmxCreateCICountEdgesChan(CtrInTaskHandle,'Dev1/ctr1','',DAQmx_Val_Rising,0,DAQmx_Val_CountUp),CtrInTaskHandle);
//timing
ErrorCheck(DAQmxCfgSampClkTiming(CtrInTaskHandle,'/Dev1/Ctr0InternalOutput',1000.0,DAQmx_Val_Rising,DAQmx_Val_ContSamps,1000),CtrInTaskHandle);
//start counter input task
ErrorCheck(DAQmxStartTask(CtrInTaskHandle),CtrInTaskHandle);
//counting pulses
ErrorCheck(DAQmxReadCounterU32(CtrIntaskHandle,1000,10.0,@data,1000,@reads,Nil),CtrIntaskHandle);
writeln('acquired samples: ',reads);
for i:=0 to 10 do writeln('sample[',i,'] = ',data[i]);
//stop and clear tasks
DAQmxStopTask(CtrInTaskHandle);
DAQmxClearTask(CtrInTaskHandle);
DAQmxStopTask(CtrOutTaskHandle);
DAQmxClearTask(CtrOutTaskHandle);
end.
TESTED HARDWARE
Examples were tested under Linux 32-bit (kernel 2.6.32) NI-DAQmx 8.0.2 and Windows 7 32-bit NI-DAQmx 14 on cards:
- NI PCI-6250
- NI PCI-6224
- NI PXIe-6612 (Windows only)
- NI USB-6356 (Windows only)
- NI USB-6003 (Windows only)
NI-DAQxmxBase examples
Generally, NI-DAQmxBase is a light version of NI-DAQmx, but this library is multiplatform. You can use it under all supported operation systems without modification of NI-DAQmxBase function call.
Read readme file to check card supported features!!!
DEVICE INFO
Functions, which provide device and channel information, are not implemented in this library, yet.
ANALOG INPUTS/OUTPUTS
Acquire finite number of samples from one analog channel
program aichannel;
{$mode objfpc}{$H+}
uses
{$IFDEF UNIX}{$IFDEF UseCThreads}
cthreads,
{$ENDIF}{$ENDIF}
Classes,nidaqmxbase;
{ you can add units after this }
var
AITaskHandle: PTaskHandle;
NiBool:Pnibool;
reads:longint=0;
i:byte;
data:array [1..1000] of double;
procedure ErrorCheck(AError:longint;ATaskHandle:PTaskHandle);
var
errBuffer:array[0..2048] of char;
errMessage:string;
begin
//get error description
if DAQmxFailed(AError) = niTrue then begin
DAQmxBaseGetExtendedErrorInfo(ErrBuffer,2048);
writeln(ErrBuffer);
//stop and cleat task
if Assigned(ATaskHandle) then begin
DAQmxBaseStopTask(ATaskHandle);
DAQmxBaseClearTask(ATaskHandle);
end;
//stop program
Halt;
end;
end;
begin
//create task
ErrorCheck(DAQmxBaseCreateTask ('', AITaskHandle),AITaskHandle);
//create analog input channel
ErrorCheck(DAQmxBaseCreateAIVoltageChan(AITaskHandle,'Dev1/ai0','', DAQmx_Val_RSE,-10, 10,DAQmx_Val_Volts,''),AITaskHandle);
//timing
//clock frequency 1000 Hz, sample rate 1000 per second
//if you use more than one active channel, generally sample rate = clock frequency/(active analog channles*10);
ErrorCheck(DAQmxBaseCfgSampClkTiming (AITaskHandle,'OnboardClock',1000,DAQmx_Val_Rising,DAQmx_Val_FiniteSamps,1000),AITaskHandle);
//start task
ErrorCheck(DAQmxBaseStartTask(AITaskHandle),AITaskHandle);
//read 1000 samples
ErrorCheck(DAQmxBaseReadAnalogF64 (AITaskHandle, 1000, 10.0,DAQmx_Val_GroupByChannel,data,1000,reads,NIBool^),AITaskHandle);
//acquired sample number
writeln(reads,' samples were acqiured');
//show value of first ten samples
for i:=1 to 10 do writeln('sample[',i,'] = ',data[i]:4:2,' V');
//stop and clear task
DAQmxBaseStopTask(AITaskHandle);
DAQmxBaseClearTask(AITaskHandle);
end.
Output example +5V connected to pin 68 on NI PCI-6250
1000 samples were acqiured
sample[1] = 5.07 V
sample[2] = 5.06 V
sample[3] = 5.06 V
sample[4] = 5.06 V
sample[5] = 5.06 V
sample[6] = 5.06 V
sample[7] = 5.06 V
sample[8] = 5.06 V
sample[9] = 5.06 V
sample[10] = 5.07 V
Continuously acquire samples from three analog inputs
program ai3contacq;
{$mode objfpc}{$H+}
uses
{$IFDEF UNIX}{$IFDEF UseCThreads}
cthreads,
{$ENDIF}{$ENDIF}
Classes,nidaqmxbase;
{ you can add units after this }
var
AITaskHandle: PTaskHandle;
NiBool:Pnibool;
reads:longint=0;
totalreads:longint=0;
i:byte;
data:array of double;
acqnumsamples:longint;
procedure ErrorCheck(AError:longint;ATaskHandle:PTaskHandle);
var
errBuffer:array[0..2048] of char;
errMessage:string;
begin
//get error description
if DAQmxFailed(AError) = niTrue then begin
DAQmxBaseGetExtendedErrorInfo(ErrBuffer,2048);
writeln(ErrBuffer);
//stop and cleat task
if Assigned(ATaskHandle) then begin
DAQmxBaseStopTask(ATaskHandle);
DAQmxBaseClearTask(ATaskHandle);
end;
//stop program
Halt;
end;
end;
begin
//enter number of total samples for each channel to be acquired
write('Enter a number of samples for each channel to be acquired: ');
readln(acqnumsamples);
//Set buffer size = length of data array:=number of active channels * sample per channel
Setlength(data,3*1000);
//create task
ErrorCheck(DAQmxBaseCreateTask ('', AITaskHandle),AITaskHandle);
//create analog input channel - 3 active analog inputs
ErrorCheck(DAQmxBaseCreateAIVoltageChan(AITaskHandle,'Dev1/ai0:2','', DAQmx_Val_RSE,-10, 10,DAQmx_Val_Volts,''),AITaskHandle);
//timing
//clock frequency 10000 Hz, sample rate 1000 per second
//if you use more than one active channel, generally sample rate = clock frequency/(active analog channles*10);
ErrorCheck(DAQmxBaseCfgSampClkTiming (AITaskHandle,'OnboardClock',10000,DAQmx_Val_Rising,DAQmx_Val_ContSamps,1000),AITaskHandle);
//start task
ErrorCheck(DAQmxBaseStartTask(AITaskHandle),AITaskHandle);
//read samples
while totalreads<acqnumsamples do begin
ErrorCheck(DAQmxBaseReadAnalogF64(AITaskHandle, 1000, 10.0, DAQmx_Val_GroupByChannel,data,Length(data),reads,NIBool^),AITaskHandle);
totalreads:=totalreads+reads;
writeln('total samples readed for each channel: ',totalreads);
//show first five values for each channel
for i:=0 to 5 do writeln('chan1[',i,'] = ',data[i]:4:2,' V ','chan2[',i,'] = ',data[i+1000]:4:2,' V ','chan3[',i,'] = ',data[i+2000]:4:2,' V ');
end;
//stop and clear task
DAQmxBaseStopTask(AITaskHandle);
DAQmxBaseClearTask(AITaskHandle);
end.
Output example +5V connected to pin 68 on NI PCI-6250
Enter a number of samples for each channel to be acquired: 2000
total samples readed for each channel: 1000
chan1[0] = 5.07 V chan2[0] = 0.00 V chan3[0] = 0.03 V
chan1[1] = 5.06 V chan2[1] = -0.00 V chan3[1] = 0.03 V
chan1[2] = 5.07 V chan2[2] = -0.00 V chan3[2] = 0.02 V
chan1[3] = 5.07 V chan2[3] = -0.00 V chan3[3] = 0.02 V
chan1[4] = 5.06 V chan2[4] = -0.00 V chan3[4] = 0.02 V
chan1[5] = 5.06 V chan2[5] = -0.00 V chan3[5] = 0.01 V
total samples readed for each channel: 2000
chan1[0] = 5.06 V chan2[0] = -0.00 V chan3[0] = -0.02 V
chan1[1] = 5.07 V chan2[1] = -0.00 V chan3[1] = -0.02 V
chan1[2] = 5.06 V chan2[2] = -0.00 V chan3[2] = -0.02 V
chan1[3] = 5.07 V chan2[3] = -0.00 V chan3[3] = -0.02 V
chan1[4] = 5.06 V chan2[4] = -0.00 V chan3[4] = -0.02 V
chan1[5] = 5.06 V chan2[5] = -0.00 V chan3[5] = -0.02 V
DIGITAL INPUTS/OUTPUTS
Read readme file to check supported card features by NI-DAQmxBase.
In case of M-series cards, correlated digital input/output is limited to about 100kHz, because DMA data transfer is not supported.
Software timed digital input
program diport;
{$mode objfpc}{$H+}
uses
{$IFDEF UNIX}{$IFDEF UseCThreads}
cthreads,
{$ENDIF}{$ENDIF}
Classes,nidaqmxbase,StrUtils
{ you can add units after this };
var
DITaskHandle:PTaskHandle;
NiBool:Pnibool;
data:byte;
reads:longint=0;
procedure ErrorCheck(AError:longint;ATaskHandle:PTaskHandle);
var
errBuffer:array[0..2048] of char;
begin
//get error description
if DAQmxFailed(AError) = niTrue then begin
DAQmxBaseGetExtendedErrorInfo(ErrBuffer,2048);
writeln(ErrBuffer);
//stop and cleat task
if Assigned(ATaskHandle) then begin
DAQmxBaseStopTask(ATaskHandle);
DAQmxBaseClearTask(ATaskHandle);
end;
//stop program
Halt;
end;
end;
begin
//create task
ErrorCheck(DAQmxBaseCreateTask('', DITaskHandle),DITaskHandle);
//create digital input port
ErrorCheck(DAQmxBaseCreateDIChan(DITaskHandle,'Dev1/port0','',DAQmx_Val_ChanForAllLines),DITaskHandle);
//start task
ErrorCheck(DAQmxBaseStartTask(DITaskHandle),DITaskHandle);
//read dat form port
//use DAQmxBaseReadDigitalU8 for 8 bit port
//use DAQmxBaseReadDigitalU32 for 32 bit port
ErrorCheck(DAQmxBaseReadDigitalU8(DITaskHandle,1,10.0,DAQmx_Val_GroupByChannel,data,1,reads,NiBool^),DITaskHandle);
writeln('digital port value %',IntToBin(data,8));
//stop and clear task
DAQmxBaseStopTask(DITaskHandle);
DAQmxBaseClearTask(DITaskHandle);
end.
Output example: +5V connected to line 1 of 8-bit digital port
digital port value %00000010
Hardware timed digital input
program diporthwtimed;
{$mode objfpc}{$H+}
uses
{$IFDEF UNIX}{$IFDEF UseCThreads}
cthreads,
{$ENDIF}{$ENDIF}
Classes,nidaqmxbase,StrUtils
{ you can add units after this };
var
DITaskHandle,CtrTaskHandle:PTaskHandle;
NiBool:Pnibool;
data:array of byte;
reads:longint=0;
i:longint;
procedure ErrorCheck(AError:longint;ATaskHandle:PTaskHandle);
var
errBuffer:array[0..2048] of char;
begin
//get error description
if DAQmxFailed(AError) = niTrue then begin
DAQmxBaseGetExtendedErrorInfo(ErrBuffer,2048);
writeln(ErrBuffer);
//stop and cleat task
if Assigned(ATaskHandle) then begin
DAQmxBaseStopTask(ATaskHandle);
DAQmxBaseClearTask(ATaskHandle);
end;
//stop program
Halt;
end;
end;
begin
{********CONFIGURE COUNTER TO USE AS CLOCK FOR DIGITAL INPUT*****************}
//create counter task
ErrorCheck(DAQmxBaseCreateTask('', CtrTaskHandle),CtrTaskHandle);
//create counter output channel
//Frequency 10000 Hz, duty 0.5
ErrorCheck(DAQmxBaseCreateCOPulseChanFreq(CtrTaskHandle,'Dev1/ctr0','',DAQmx_Val_Hz,DAQmx_Val_Low,0,10000,0.5),CtrTaskHandle);
//timing
//last value is not important for continuesly sample mode, for finite sample mode = generate 10000 samples
ErrorCheck(DAQmxBaseCfgImplicitTiming(CtrTaskHandle,DAQmx_Val_ContSamps,10000),CtrTaskHandle);
//start counter task
ErrorCheck(DAQmxBaseStartTask(CtrTaskHandle),CtrTaskHandle);
{*******************HW TIMED DIGITAL INPUT***********************************
**********LIMITED TO 10kHz,DMA IS NOT IMPLEMENTED****************************}
//configure buffer for 1000 samples
SetLength(data,1000);
//create task
ErrorCheck(DAQmxBaseCreateTask('', DITaskHandle),DITaskHandle);
//create digital input port
ErrorCheck(DAQmxBaseCreateDIChan(DITaskHandle,'Dev1/port0','',DAQmx_Val_ChanForAllLines),DITaskHandle);
//timing frequency 10000Hz, 1000 sample per channel
ErrorCheck(DAQmxBaseCfgSampClkTiming(DITaskHandle,'/Dev1/Ctr0InternalOutput',10000.0,DAQmx_Val_Rising,DAQmx_Val_ContSamps,10000),DITaskHandle);
//start task
ErrorCheck(DAQmxBaseStartTask(DITaskHandle),DITaskHandle);
//read dat form port
//use DAQmxBaseReadDigitalU8 for 8 bit port
//use DAQmxBaseReadDigitalU32 for 32 bit port
ErrorCheck(DAQmxBaseReadDigitalU8(DITaskHandle,10000,10.0,DAQmx_Val_GroupByChannel,data,10000,reads,NiBool^),DITaskHandle);
writeln(reads,' samples were readed');
//show first 10 samples
for i:=0 to 9 do writeln('sample[',i,'] = %',IntToBin(data[i],8));
//stop and clear task
DAQmxBaseStopTask(DITaskHandle);
DAQmxBaseClearTask(DITaskHandle);
DAQmxBaseStopTask(CtrTaskHandle);
DAQmxBaseClearTask(CtrTaskHandle);
end.
Output example: +5V connected to line 1 of 8-bit digital port, executed with time command under Linux.
10000 samples were readed
sample[0] = %00000010
sample[1] = %00000010
sample[2] = %00000010
sample[3] = %00000010
sample[4] = %00000010
sample[5] = %00000010
sample[6] = %00000010
sample[7] = %00000010
sample[8] = %00000010
sample[9] = %00000010
real 0m4.483s
user 0m4.261s
sys 0m0.100s
Software timed digital output
program doport;
{$mode objfpc}{$H+}
uses
{$IFDEF UNIX}{$IFDEF UseCThreads}
cthreads,
{$ENDIF}{$ENDIF}
Classes,nidaqmxbase,StrUtils,SysUtils
{ you can add units after this };
var
DOTaskHandle,CtrTaskHandle:PTaskHandle;
NiBool:Pnibool;
data: byte;
written:longint=0;
i:longint;
procedure ErrorCheck(AError:longint;ATaskHandle:PTaskHandle);
var
errBuffer:array[0..2048] of char;
begin
//get error description
if DAQmxFailed(AError) = niTrue then begin
DAQmxBaseGetExtendedErrorInfo(ErrBuffer,2048);
writeln(ErrBuffer);
//stop and cleat task
if Assigned(ATaskHandle) then begin
DAQmxBaseStopTask(ATaskHandle);
DAQmxBaseClearTask(ATaskHandle);
end;
//stop program
Halt;
end;
end;
begin
//write data to buffer, produce digital waveform on all port lines
data:=255;
//create task
ErrorCheck(DAQmxBaseCreateTask('', DOTaskHandle),DOTaskHandle);
//create digital input port
ErrorCheck(DAQmxBaseCreateDOChan(DOTaskHandle,'Dev1/port0','',DAQmx_Val_ChanForAllLines),DOTaskHandle);
//use DAQmxBaseWriteDigitalU8 for 8 bit port
//use DAQmxBaseWriteDigitalU32 for 32 bit port
//set third parametr to 1 to enable autostart or set to 0 and use DAQmxBaseStartTask before
//set digital "1"
writeln('set digital 1 on all port lines');
writeln('sleep 10s');
ErrorCheck(DAQmxBaseWriteDigitalU8(DOTaskHandle,1000,1,1000,DAQmx_Val_GroupByChannel,data,written,NiTrue),DOTaskHandle);
sleep(10000);
writeln(written,' samples were written');
//set digital "0"
writeln('set digital 0 on all port lines');
writeln('sleep 10s');
sleep(10000);
ErrorCheck(DAQmxBaseWriteDigitalU8(DOTaskHandle,1000,1,1000,DAQmx_Val_GroupByChannel,data,written,NiTrue),DOTaskHandle);
writeln(written,' samples were written');
//stop and clear task
DAQmxBaseStopTask(DOTaskHandle);
DAQmxBaseClearTask(DOTaskHandle);
DAQmxBaseStopTask(CtrTaskHandle);
DAQmxBaseClearTask(CtrTaskHandle);
end.
Hardware timed digital output
Digital output generation frequency is limited to ~100kHz, because DMA is not supported by the driver .
program doporthwtimed;
{$mode objfpc}{$H+}
uses
{$IFDEF UNIX}{$IFDEF UseCThreads}
cthreads,
{$ENDIF}{$ENDIF}
Classes,nidaqmxbase,StrUtils
{ you can add units after this };
var
DOTaskHandle,CtrTaskHandle:PTaskHandle;
NiBool:Pnibool;
data:array of byte;
written:longint=0;
i:longint;
procedure ErrorCheck(AError:longint;ATaskHandle:PTaskHandle);
var
errBuffer:array[0..2048] of char;
begin
//get error description
if DAQmxFailed(AError) = niTrue then begin
DAQmxBaseGetExtendedErrorInfo(ErrBuffer,2048);
writeln(ErrBuffer);
//stop and cleat task
if Assigned(ATaskHandle) then begin
DAQmxBaseStopTask(ATaskHandle);
DAQmxBaseClearTask(ATaskHandle);
end;
//stop program
Halt;
end;
end;
begin
{********CONFIGURE COUNTER TO USE AS CLOCK FOR DIGITAL INPUT*****************}
//create counter task
ErrorCheck(DAQmxBaseCreateTask('', CtrTaskHandle),CtrTaskHandle);
//create counter output channel
//Frequency 10000 Hz, duty 0.5
ErrorCheck(DAQmxBaseCreateCOPulseChanFreq(CtrTaskHandle,'Dev1/ctr0','',DAQmx_Val_Hz,DAQmx_Val_Low,0,10000,0.5),CtrTaskHandle);
//timing
//last value is not important for continuesly sample mode, for finite sample mode = generate 10000 samples
ErrorCheck(DAQmxBaseCfgImplicitTiming(CtrTaskHandle,DAQmx_Val_ContSamps,10000),CtrTaskHandle);
//start counter task
ErrorCheck(DAQmxBaseStartTask(CtrTaskHandle),CtrTaskHandle);
{*******************HW TIMED DIGITAL INPUT***********************************
**********LIMITED TO 10kHz,DMA IS NOT IMPLEMENTED****************************}
//configure buffer for 1000 samples
SetLength(data,1000);
//write data to buffer, produce digital waveform on all port lines
for i:=0 to 999 do if (i mod 2 = 0) then data[i]:=255;
//create task
ErrorCheck(DAQmxBaseCreateTask('', DOTaskHandle),DOTaskHandle);
//create digital input port
ErrorCheck(DAQmxBaseCreateDOChan(DOTaskHandle,'Dev1/port0','',DAQmx_Val_ChanForAllLines),DOTaskHandle);
//timing frequency 10000Hz, 1000 sample per channel
ErrorCheck(DAQmxBaseCfgSampClkTiming(DOTaskHandle,'/Dev1/Ctr0InternalOutput',10000.0,DAQmx_Val_Rising,DAQmx_Val_ContSamps,1000),DOTaskHandle);
//use DAQmxBaseWriteDigitalU8 for 8 bit port
//use DAQmxBaseWriteDigitalU32 for 32 bit port
//set third parametr to 1 to enable autostart or set to 0 and use DAQmxBaseStartTask before
ErrorCheck(DAQmxBaseWriteDigitalU8(DOTaskHandle,1000,1,1000,DAQmx_Val_GroupByChannel,data,written,NiTrue),DOTaskHandle);
writeln(written,' samples were written');
//stop and clear task
DAQmxBaseStopTask(DOTaskHandle);
DAQmxBaseClearTask(DOTaskHandle);
DAQmxBaseStopTask(CtrTaskHandle);
DAQmxBaseClearTask(CtrTaskHandle);
end.
COUNTER INPUTS/OUTPUTS
Counter input of M-series cards is limited to computer speed.
COUNTER OUTPUT
Counter output can be timed by software or hardware.
Example demontrate how to use couter ouput as frequency generator(clock signal for other hardware) or as basic pwm regulation.
In this example counter output is hardware timed.
program ctrout;
{$mode objfpc}{$H+}
uses
{$IFDEF UNIX}{$IFDEF UseCThreads}
cthreads,
{$ENDIF}{$ENDIF}
Classes,nidaqmxbase,StrUtils,SysUtils
{ you can add units after this };
var
CtrTaskHandle:PTaskHandle;
NiBool:Pnibool;
data:array of byte;
reads:longint=0;
procedure ErrorCheck(AError:longint;ATaskHandle:PTaskHandle);
var
errBuffer:array[0..2048] of char;
begin
//get error description
if DAQmxFailed(AError) = niTrue then begin
DAQmxBaseGetExtendedErrorInfo(ErrBuffer,2048);
writeln(ErrBuffer);
//stop and cleat task
if Assigned(ATaskHandle) then begin
DAQmxBaseStopTask(ATaskHandle);
DAQmxBaseClearTask(ATaskHandle);
end;
//stop program
Halt;
end;
end;
begin
{********CONFIGURE COUNTER TO USE AS CLOCK FOR DIGITAL INPUT*****************}
//create counter task
ErrorCheck(DAQmxBaseCreateTask('', CtrTaskHandle),CtrTaskHandle);
//create counter output channel
//Frequency 10000 Hz, duty 0.5
ErrorCheck(DAQmxBaseCreateCOPulseChanFreq(CtrTaskHandle,'Dev1/ctr0','',DAQmx_Val_Hz,DAQmx_Val_Low,0,10000,0.5),CtrTaskHandle);
//timing
//last value is not important for continuesly sample mode, for finite sample mode = generate 10000 samples
ErrorCheck(DAQmxBaseCfgImplicitTiming(CtrTaskHandle,DAQmx_Val_ContSamps,10000),CtrTaskHandle);
//start counter task
ErrorCheck(DAQmxBaseStartTask(CtrTaskHandle),CtrTaskHandle);
//generate frequency signal for 10 seconds
sleep(10000);
DAQmxBaseStopTask(CtrTaskHandle);
DAQmxBaseClearTask(CtrTaskHandle);
end.
COUNTER INPUT
Counter input is only software operated. It is limited by hardware driver.
program ctrin;
{$mode objfpc}{$H+}
uses
{$IFDEF UNIX}{$IFDEF UseCThreads}
cthreads,
{$ENDIF}{$ENDIF}
Classes,nidaqmxbase,StrUtils,SysUtils,Crt
{ you can add units after this };
var
CtrInTaskHandle:PTaskHandle;
NiBool:Pnibool;
data:dword=0;
reads:longint=0;
procedure ErrorCheck(AError:longint;ATaskHandle:PTaskHandle);
var
errBuffer:array[0..2048] of char;
begin
//get error description
if DAQmxFailed(AError) = niTrue then begin
DAQmxBaseGetExtendedErrorInfo(ErrBuffer,2048);
writeln(ErrBuffer);
//stop and cleat task
if Assigned(ATaskHandle) then begin
DAQmxBaseStopTask(ATaskHandle);
DAQmxBaseClearTask(ATaskHandle);
end;
//stop program
Halt;
end;
end;
begin
{*****************CREATE COUNTER INPUT***************************************}
//create couter input task
ErrorCheck(DAQmxBaseCreateTask('Counter input task',CtrInTaskHandle),CtrInTaskHandle);
//create input counter for pulse counting
ErrorCheck(DAQmxBaseCreateCICountEdgesChan(CtrInTaskHandle,'Dev1/ctr1','',DAQmx_Val_Rising,0,DAQmx_Val_CountUp),CtrInTaskHandle);
//timing
//ErrorCheck(DAQmxBaseCfgSampClkTiming(CtrInTaskHandle,'/Dev1/Ctr0InternalOutput',1000.0,DAQmx_Val_Rising,DAQmx_Val_ContSamps,1000),CtrInTaskHandle);
//start counter input task
ErrorCheck(DAQmxBaseStartTask(CtrInTaskHandle),CtrInTaskHandle);
//counting pulses
writeln('press any key to stop counting');
repeat
ErrorCheck(DAQmxBaseReadCounterU32(CtrIntaskHandle,1,10.0,data,1,reads,NiTrue),CtrIntaskHandle);
writeln('counter value: ',data);
until keypressed;
//clear and stop task
DAQmxBaseStopTask(CtrInTaskHandle);
DAQmxBaseClearTask(CtrInTaskHandle);
end.
TESTED HARDWARE
Examples were tested under Scientific Linux 6.4, Mageia 2 32-bit and Windows 32-bit and should work under MacOS (need test) on cards:
- NI PCI-6250
- NI PCI-6224
- NI USB-6356 (Windows only)
