I've got two USB-6210 devices that I need to sync up so that they
both gather data at exactly the same time. I'd like to trigger the data
gathering for each device by sending a trigger out of Dev1/PFI6 and
having both devices receive the trigger on PFI0.
I''ve tried using the ai example program that receives an analog start trigger and it doesn't seem to work. Here's the code I tried:
/*********************************************************************
*
* ANSI C Example program:
* acquireNScans-AnlgStart.c
*
* Example Category:
* AI
*
* Description:
* This example demonstrates how to acquire a finite amount of data
* using the DAQ device's internal clock, started by an analog edge
* condition.
*
* Instructions for Running:
* 1. Select the physical channel to correspond to where your
* signal is input on the DAQ device.
* 2. Enter the minimum and maximum voltage range.
* Note: For better accuracy try to match the input range to the
* expected voltage level of the measured signal.
* 3. Set the number of samples to acquire per channel.
* 4. Set the rate of the acquisiton.
* Note: The rate should be AT LEAST twice as fast as the maximum
* frequency component of the signal being acquired.
* 5. Set the source of the start trigger. By default this is
* analog input channel 0.
* 6. Set the slope and level of desired analog edge condition.
*
* Steps:
* 1. Create a task.
* 2. Create an analog input voltage channel.
* 3. Set the rate for the sample clock. Additionally, define the
* sample mode to be finite.
* 4. Define the parameters for an Analog Slope Start Trigger.
* 5. Call the Start function to start the acquistion.
* 6. Read all of the waveform data.
* 7. Call the Clear Task function to stop the acquistion.
* 8. Display an error if any.
*
* I/O Connections Overview:
* Make sure your signal input terminal matches the Physical
* Channel I/O Control. In this case wire your signal to the ai0
* pin on your DAQ Device. The analog start trigger must be connected
* to PFI0.
*
* Recommended Use:
* 1. Call Configure and Start functions.
* 2. Call Read function.
* 3. Call Stop function at the end.
*
*********************************************************************/
#include "NIDAQmxBase.h"
#include <stdio.h>
#define DAQmxErrChk(functionCall) { if( DAQmxFailed(error=(functionCall)) ) { goto Error; } }
int main(int argc, char *argv[])
{
// Task parameters
int32 error = 0;
TaskHandle taskHandle = 0;
char errBuff[2048]={'\0'};
int32 i;
// Channel parameters
char chan[] = "Dev1/ai0";
float64 min = -10.0;
float64 max = 10.0;
// Timing parameters
char clockSource[] = "OnboardClock";
uInt64 samplesPerChan = 1000;
float64 sampleRate = 10000.0;
// Triggering parameters
//orig char triggerSource[] = "PFI0";
char triggerSource[] = "/Dev1/PFI0";
uInt32 triggerSlope = DAQmx_Val_RisingSlope;
float64 triggerLevel = 1.0;
// Data read parameters
#define bufferSize (uInt32)1000
float64 data[bufferSize];
int32 pointsToRead = bufferSize;
int32 pointsRead;
float64 timeout = 10.0;
DAQmxErrChk (DAQmxBaseCreateTask("",&taskHandle));
DAQmxErrChk (DAQmxBaseCreateAIVoltageChan(taskHandle,chan,"",DAQmx_Val_Cfg_Default,min,max,DAQmx_Val_Volts,NULL));
DAQmxErrChk (DAQmxBaseCfgSampClkTiming(taskHandle,clockSource,sampleRate,DAQmx_Val_Rising,DAQmx_Val_FiniteSamps,samplesPerChan));
printf("Calling CfgAnlgEdgeStartTrig with %s...\n", triggerSource);
DAQmxErrChk (DAQmxBaseCfgAnlgEdgeStartTrig(taskHandle,triggerSource,triggerSlope,triggerLevel));
printf("Done with StartTrig.\n");
DAQmxErrChk (DAQmxBaseStartTask(taskHandle));
DAQmxErrChk (DAQmxBaseReadAnalogF64(taskHandle,pointsToRead,timeout,DAQmx_Val_GroupByChannel,data,bufferSize,&pointsRead,NULL));
printf ("Acquired %d samples\n", pointsRead);
// Just print out the first 10 points
for (i = 0; i < 10; ++i)
printf ("data[%d] = %f\n", i, data[i]);
Error:
if( DAQmxFailed(error) )
DAQmxBaseGetExtendedErrorInfo(errBuff,2048);
if(taskHandle != 0) {
DAQmxBaseStopTask (taskHandle);
DAQmxBaseClearTask (taskHandle);
}
if( DAQmxFailed(error) )
printf ("DAQmxBase Error %d: %s\n", error, errBuff);
return 0;
}
and here is the result from running the program:
$ ./acquireNScans-AnlgStart
Calling CfgAnlgEdgeStartTrig with /Dev1/PFI0...
DAQmxBase Error -200428: Value passed to the Task/Channels In control is invalid.
The NIDAQ-mx README.txt file says this is supported for USB-621X. Can anyone tell me why this isn't working?
