WriteDigChan-ExtClk

Hello,
I ran the sample program
C:\Users\Public\Documents\National Instruments\NI-DAQ\Examples\DAQmx ANSI C\Digital\Generate Values\Write Dig Chan-Ext Clk, but got a message as below:
DAQmx Error: Requested value is not a supported value for this property. The pro
perty value may be invalid because it conflicts with another property.
Property: DAQmx_SampTimingType
Requested Value: DAQmx_Val_SampClk
You Can Select: DAQmx_Val_OnDemand
Task Name: _unnamedTask<0>
Status Code: -200077
End of program, press Enter key to quit.
I'm using USB-6001 and nothing is connected to it except usb cable.
Could you give any advice regarding this error?
Thanks!

If you can use the Analog Output lines for this task (i.e. you are not already using them for something else) you will be much better off--they can be clocked at up to 5 kHz.
If not, you'll have to use software-timed digital output--I wouldn't consider the timing of this particularly accurate but it might be useable for some applications.
Best Regards,
John Passiak

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Hello VJohnson,
The counter will give you control of the clock frequency and duty cycle. However, this card also has correlated DIO, which means that you can clock your digital lines. Because of this, you can write a specific pattern (101010) to the buffer and just have it continuously output. However, you will have to write this in a way that you know what values you're writing based on the part of the clock you're at.
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Hi Graham
I'm out of the lab today but I'll try and answer your questions as best I can...
1) What are the values you have set for Buffer size, Rate, samples per read and post trigger Samples?
At the moment I have all the values (e.g. sample rate, buffer size etc) unchanged apart from the ones I mentioned in my previous post (see above). I have in the past played around with changing the buffer sizes and rates in the example VI but as this appeared to have no effect on the behaviour I now have them setup as in the download.
2) Does the program end after the stop trigger is implemented?
Yep, if I toggle the trigger line high then low I see the program exits the read loop and the VI stops running as expected.
3) Lastly can you give me the details of triggering method. Are you
using a digital train of users set digital pulses? how long is the
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I need to measure the frequency of a signal on Pin 39 (PFI 15) of a PXIe-6361 module.

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CLA, CPI, AIA-Vision
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NI9403:Acquisition & Génération bufferisée

Bonjour,
Je souhaite réaliser une acquisition / génération avec un module 9403 en cDAQ sous Visual C++.
J’ai modifié un des exemples NI DAQMX Ansi C (le code est ci dessous) de manière à initialiser la tache DI et la tache DO. Cependant, je suis confronté à un problème de routage de clock.
* ANSI C Example program:
* ContReadDigChan-ExtClk.c
* Example Category:
* DI
* Description:
* This example demonstrates how to input a continuous digital
* waveform using an external clock.
* Instructions for Running:
* 1. Select the physical channel to correspond to where your
* signal is input on the DAQ device.
* 2. Select the Clock Source for the acquistion.
* 3. Set the approximate Rate of the external clock. This allows
* the internal characteristics of the acquisition to be as
* efficient as possible. Also set the Samples to Read control.
* This will determine how many samples are read each time. This
* also determines how many points are plotted on the graph each
* iteration.
* Steps:
* 1. Create a task.
* 2. Create a Digital Input channel.
* 3. Define the parameters for an External Clock Source.
* Additionally, set the sample mode to be continuous.
* 4. Call the Start function to start the acquisition.
* 5. Read the waveform data continuously until the user hits the
* stop button or an error occurs.
* 6. Call the Clear Task function to clear the Task.
* 7. Display an error if any.
* I/O Connections Overview:
* Make sure your signal input terminal matches the Physical
* Channel I/O control. Also, make sure your external clock
* terminal matches the Physical Channel I/O Control. For further
* connection information, refer to your hardware reference manual.
#include <stdio.h>
#include <NIDAQmx.h>
#define DAQmxErrChk(functionCall) if( DAQmxFailed(error=(functionCall)) ) goto Error; else
int32 CVICALLBACK DoneCallback(TaskHandle taskHandle, int32 status, void *callbackData);
int main(void)
int32 error=0;
TaskHandle DItaskHandle=0,DOtaskHandle=0;
uInt32 data[1000],dataOut[1000];
int32 sampsRead,totalRead=0;
char errBuff[2048]={'\0'};
int i;
// DAQmx Configure Code
DAQmxErrChk (DAQmxCreateTask("TacheDI",&DItaskHandle));
DAQmxErrChk (DAQmxCreateDIChan(DItaskHandle,"cDAQ1Mod8/port0/line0:15","",DAQmx_Val_ChanForAllLines));
DAQmxErrChk (DAQmxCfgSampClkTiming(DItaskHandle,NULL,10000.0,DAQmx_Val_Rising,DAQmx_Val_ContSamps,1000));
DAQmxErrChk (DAQmxCreateTask("TacheDO",&DOtaskHandle));
DAQmxErrChk (DAQmxCreateDOChan(DOtaskHandle,"cDAQ1Mod8/port0/line16:31","",DAQmx_Val_ChanForAllLines));
DAQmxErrChk (DAQmxCfgSampClkTiming(DOtaskHandle,NULL,10000.0,DAQmx_Val_Rising,DAQmx_Val_ContSamps,1000));
// DAQmx Start Code
DAQmxErrChk (DAQmxStartTask(DItaskHandle));
for(i=0;i<1000;++i)
dataOut[i] = i;
DAQmxErrChk (DAQmxRegisterDoneEvent(DOtaskHandle,0,DoneCallback,NULL));
DAQmxErrChk (DAQmxWriteDigitalU16(DOtaskHandle,1000,0,10.0,DAQmx_Val_GroupByChannel,dataOut,NULL,NULL));
DAQmxErrChk (DAQmxStartTask(DOtaskHandle));
printf("Acquiring samples continuously. Press Ctrl+C to interrupt\n");
while( 1 ) {
// DAQmx Read Code
DAQmxErrChk (DAQmxReadDigitalU16(DItaskHandle,1000,10.0,DAQmx_Val_GroupByChannel,data,1000,&sampsRead,NULL));
if( sampsRead>0 ) {
totalRead += sampsRead;
printf("Acquired %d samples. Total %d\r",sampsRead,totalRead);
fflush(stdout);
printf("\nAcquired %d total samples.\n",totalRead);
Error:
if( DAQmxFailed(error) )
DAQmxGetExtendedErrorInfo(errBuff,2048);
if( DItaskHandle!=0 ) {
// DAQmx Stop Code
DAQmxStopTask(DItaskHandle);
DAQmxClearTask(DItaskHandle);
if( DOtaskHandle!=0 ) {
// DAQmx Stop Code
DAQmxStopTask(DOtaskHandle);
DAQmxClearTask(DOtaskHandle);
if( DAQmxFailed(error) )
printf("DAQmx Error: %s\n",errBuff);
printf("End of program, press Enter key to quit\n");
getchar();
return 0;
int32 CVICALLBACK DoneCallback(TaskHandle taskHandle, int32 status, void *callbackData)
int32 error=0;
char errBuff[2048]={'\0'};
static int count=0;
int i;
uInt32 dataOut[1000];
for(i=0;i<1000;++i)
dataOut[i] = i+count;
count++;
DAQmxErrChk (DAQmxWriteDigitalU16(taskHandle,1000,0,10.0,DAQmx_Val_GroupByChannel,dataOut,NULL,NULL));
// Check to see if an error stopped the task.
DAQmxErrChk (status);
Error:
if( DAQmxFailed(error) ) {
DAQmxGetExtendedErrorInfo(errBuff,2048);
DAQmxClearTask(taskHandle);
printf("DAQmx Error: %s\n",errBuff);
return 0;
Voici le message d’erreur obtenu:
Specified route cannot be satisfied, because it requires resources that are currently in use by another route.
Source Device: cDAQ1
Source Terminal: do/SampleClock
Destination Device: cDAQ1
Destination Terminal: Slot8/ConvertPulse
Required Resources in Use by
Task Name: TacheDI
Source Device: cDAQ1
Source Terminal: di/SampleClock
Destination Device: cDAQ1
Destination Terminal: Slot8/ ConvertPulse
Task Name: TacheDO
Status Code : -89137
Comment puis-je procéder pour effectuer à la fois une init de la carte en mode DI et DO avec la clock interne ?

Re jmali666,
Je vous renvoi vers le lien de la datasheet de ce module: Datasheet 9403
En fait vous ne pouvez cadencer matériellement que si vous ne faites qu'une lecture OU qu'une écriture comme il est spécifié dans la Datasheet.
Si vous faites les deux cumulées, alors il vous faudra cadencer logiciellement.
J'ai fait qlq tests (reproduction de votre erreur) sur labview et je vous le confirme. Veuillez trouvez ci joint des captures d'écrans.
Cordialement
Pierre_D
National Instruments France
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What is max number of bits supported by the 2nd argument of DAQmxCreateDOChan()?

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Hello JoeCz,
Thank you for using NI forums. The number of bits for each port is device specific, but most devices do have 8 bits for each port. One thing you can try is to specify multiple ports i.e. "Dev1/port0/line0:7, Dev1/port1/line0:7". You can then create an 8 bit array with two elements (1 element for each port) and specify the values you would like written for each line. Try this out and let me know how it works for you.
Regards,

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hello,
Thanks for all the explanations, using the function outside the loop, she generates a file of 1000 lines, but by using it in the loop with numchannels =2 (for example) she generates two columns 500 lines, now I see clearly the difference.
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--------------------Configuration: TestDaq2 - Win32 Debug--------------------
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Attachments:
erreur.jpg ‏144 KB

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if (!(status = DIG_Block_PG_Config( m_deviceNumber,
                                               m_group,
                                               1,           /* Enable pattern generation using REQ edge latching */
                                               1,           /* REQ source - External REQ */
                                               -3,           /* timebase - 50ns this is for internal clock */
                                               1,           /* REQ interval */
                                               (i16) 0)))   /* enable or disable external gating */
Can you help me how to make it run with DAQmx? Thanks.
Solved!
Go to Solution.

Hi,
Have you tried running one of the C examples included with DAQmx? The example ContReadDigChan-ExtClk.c (NI-DAQ->Examples->DAQmx ANSI C->Digital->Read Values->Cont Read Dig Chan-Ext Clk) appears to be somewhat similar to your application and may help narrow down the problem a bit more.
James K.
National Instruments
Applications Engineer

WriteDigChan-ExtClk

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