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yipilipi
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NI 6602 how to synchronize frequency counter

Hi, i'm working with a NI 6602 board. Actually we have 3 optical encoder connected to ctr0 (pfi38), crt1(PFI34)  and ctr2(PFI30). I need to have synchronous acquisition of frequency. I'm using NI-DAQMX with C . Our goal is to display frequency variation between the 3 entry.

I think using  edge count can be a better way to have synched samples but actually i can't change wiring and cannot connect my source signal to pfi39, pfi35 and pfi31.  I've tried to use  DAQmxSetCICountEdgesTerm(taskHandle,"Dev2/ctr0","Dev2/PFI38") , i have the error  -89120 (signal can't be routed). When i set  DAQmxSetCICountEdgesTerm(taskHandle,"Dev2/ctr0source","Dev2/PFI38") no error but always count 0.

My signal frequency is betwenn 0 and 16000hz.

 

 

My code is below

DAQmxErrChk (DAQmxCreateCOPulseChanTime(taskHandleOut,
       "Dev2/ctr4",  // gating pulse generated
       "channel 1",
       DAQmx_Val_Seconds, // units
       DAQmx_Val_Low, // resting state
       0.0,  // initial delay
       0.5,  // pulse train freq 0.,
                                                    
          0.5));  // pulse shape
 DAQmxErrChk (DAQmxCfgImplicitTiming( taskHandleOut,
      DAQmx_Val_ContSamps,
      0));

DAQmxErrChk (DAQmxCreateCICountEdgesChan( taskHandle,
       "Dev2/ctr0",
       "channel 0",
       DAQmx_Val_Rising,
       0,   // initial count
       DAQmx_Val_CountUp)); // count direction

 DAQmxErrChk (DAQmxCfgSampClkTiming( taskHandle,
      "/Dev2/Ctr4InternalOutput", // sample clock set to pulse gen
      20000000.0,    // max expected rate of sample clock
      DAQmx_Val_Rising,
      DAQmx_Val_ContSamps,
      10000000));    // buffer size
  DAQmxSetCICountEdgesTerm(taskHandle,"Dev2/ctr0source","Dev2/PFI38");

 

Regards

 

Active Participant
Remi.D
Posts: 435
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Re : NI 6602 how to synchronize frequency counter

Hi yipilipi,

 

To make edge count, you need to put your signal on the counter sources pin. If not you will not get counts!

 

Regards,

Rémi D.
National Instruments France

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