Synchronize ai reading with pfi signal

Hi,

I am a first time user.

I have an signal on Dev/ai1 1Mhz and I have digital signal on PFI0 about 800Hz (it can change in time from 760-815 HZ)

I have to read 700 samples (in continuous mode) from ai1 when signal on PFI0 is high.

I find one decision -  generate pulse and use it like external clock.

Here is my code

/*PULSE*/

errorCheck (DAQmxCreateTask("",&pulseTask));

errorCheck(DAQmxCreateCOPulseChanFreq(pulseTask,"Dev1/ctr0","",DAQmx_Val_Hz,DAQmx_Val_High ,0.0,1000000.0,0.5));

errorCheck (DAQmxCfgDigEdgeStartTrig(pulseTask,"/Dev1/PFI0",DAQmx_Val_Falling));

errorCheck (DAQmxCfgImplicitTiming(pulseTask,DAQmx_Val_FiniteSamps,700));

errorCheck(DAQmxSetStartTrigRetriggerable(pulseTask, 1));

errorCheck(DAQmxStartTask(pulseTask));

/*END PULSE*/

/*READ DATA */

float64 ddd[14000];

int32 cnt;

errorCheck(DAQmxCreateTask("",&aiTask));

errorCheck(DAQmxCreateAIVoltageChan(aiTask,"Dev1/ai1","",DAQmx_Val_Diff,-5.0,5.0,DAQmx_Val_Volts,NULL));

errorCheck(DAQmxCfgSampClkTiming(aiTask,"/Dev1/PFI12",800000,DAQmx_Val_Rising,DAQmx_Val_ContSamps,7000));

errorCheck(DAQmxCfgDigEdgeStartTrig(aiTask,"/Dev1/PFI0",DAQmx_Val_Rising));

errorCheck(DAQmxStartTask(aiTask));

while(1){

errorCheck(DAQmxReadAnalogF64(aiTask,700,-1,DAQmx_Val_GroupByChannel,ddd,700,&cnt,NULL));

//code ...

}

DAQmxStopTask(aiTask);

DAQmxClearTask(aiTask);

This code works well. But my device support only one pulse gen. And I need gen. pulse in another task.

I don't know how to solve this problem. How to synchronize ai reading with pfi signal?