DC pulse output analog input
I am using a 6221 PCI DAQ card and attempting to put out a DC level for a several different times. During the output of each DC level I need to sample two DC inputs via the analog input. Most of my DC levels last for 100s of seconds each and a sample rate of 1S/s on the analog inputs is OK.
My problem arises when I attempt to place a 30ms pulse into the analog output. During this 30ms I need to increase the data rate of the analog input.
I have attempted to use a while loop to control the time between changes but can not get the sampling rates correct to allow for the correct number of samples.
On suggestion has been to take all data at a fast rate. The test will last in excess of 3000 seconds and I get way too much data at a fast rate.
I need to be able to change data rates on the fly as I change the DC levels.
Does any one have any ideas?
Thanks,
John@Saft wrote:
I know when the pulse is to arrive before it happens. I have an array of data including voltage outputs, duration of output, and what data rate to sample at.
My problem is insuring the sampling starts before the pulse arrives and continues for the duration of the pulse.
One way I'm sure can work uses "Continuous Acquisition. "See: "Cont Acq&Graph Voltage-Analog SW Trigger.vi" example.
If the DAQ-rate is known before leading-edge of pulse, then, start the Acquisition at whatever frequency's needed, making the input buffer bigger than required, then when the end-of-pulse arrives, reach-into the input buffer and pull-out the "pulse". With a little work you may find an example that uses a "stop-trigger"
There may be a "slick" way to do this without "Continuous Acquisition" using a parameter called "Pre-trigger" scans. My first LV project (circa- 1990) used this, and I've done it with at least one "E"-series board, but not yet under DAQ-MX - and couldn't find an example with Internal clock, External Trigger.
Cheers!
"Inside every large program is a small program struggling to get out." (attributed to Tony Hoare)
Similar Messages
-
Labviewcode wanted to count pulses from analog input
Can somebody help me with the following problem?
I don't have a Data Aquisition board so I use my steppermotor controller, the MID-7604, and it's analog input to read from a
sensor (photointerrupter) which outputs 0 or +5 Volts. I want to count how many times an output of 5 Volts appears.
The problem is that the signal is not a Waveform, so the Daq functions in Labview won't work. I've tried to generate a waveform
from the signal but also no results.
What I have created now is a counter which counts every signal above an adjusted value. The problem is that it counts on and on
when the signal is above the value, I want it to count one time. (like a trigger which detect a low to high level signal)
In the attachment you see that program and an other I've found (event counter) doing what I want, but I haven't been able to transform it in to
my own problem. Please help me on this because I'm stuck right now.
Thanks in advance
Message Edited by Trabuca on 07-04-2005 02:56 AM
Attachments:
monitor ain pulses with display.vi 31 KB
Event_Counter.vi 39 KBHi,
there are some ways - one is using a shift-register.
Attached is a flank detector - each time "Boolean" changes from 0 to 1 or 1 to 0 the count is increased by one.
I hope that helps
Greez
Stefan
Message Edited by mycroft on 07-05-2005 06:41 AM
Message Edited by mycroft on 07-05-2005 06:41 AM
Attachments:
Change detector_LV.GIF 9 KB -
How to use counter output pulses to trigger analog input?
Hello all,
I hope the kind people using this forum can help me, a lowly beginner LV programmer! I have been attempting to create a VI that produces a user defined number of TTL pulses, separated by every n seconds. Each TTL would be outputted to a stimulator, which in turn generates its own TTL. Using the stimulator-generated TTL, I would like to trigger finite analog data acquisition (e.g. for every TTL, trigger the collection of a data sweep that contains 4000 samples (collected at 4000 Hz), with 1000 samples collected pre-trigger. I would like to also be able to see each data sweep as it is triggered on a chart. As I understand things (lots of online/book/forum reading), I should be using the counter output to generate my TTL pulses, and syncing each counter produced TTL with analog input, as well as using a reference trigger. Also, the AI part should be started first, so that I don' t miss any counter outputs. If it matters, I also need to use one of the AI channels to acquire the TTL, so I can see my stimulator-induced responses to the stimulator in time.
I am able to generate the TTL pulses from the counter output, but I am having a problem with the AI part. I am unsure how to sync the counter output with AI. Also, since I need to acquire pre-trigger samples, I would be needing to acquire samples continuously, but when I set 'continuous samples' on daqmx timing, the VI doesn't work (hence why's its set to 'finite samples').
I hope someone out there can help, as I have been at this for what seems ages, with limited success. I am using a USB-6259 and LabView v8.2. Thanks!
Attachments:
RC001 v_1.vi 49 KBHello,
Due to the fact that analog tasks themselves are not retriggerable, a
pulse train produced by a counter is always used as the sample clock
for the analog input task in order to recreate a retriggerable effect
for analog input. This can be done by creating a finite pulse train set
to retriggerable using the DAQmx Trigger Property Node, or the pulse
train could be continuous and just be gated by another signal. Neither
of these methods can be properly applied in hardware to create a
retriggerable reference trigger. You can however implement something
similar in software by just stopping and restarting your reference
triggered analog input task within a loop. There will be some delay
between when the task is stopped and restarted, as these events require
software intervention, but if there is enough time between when each
trigger signal is generated, there should not be any noticeable delay
or missed samples.
I have attached an example of this!
Mark B
===If this fixes your problem, mark as solution!===
Attachments:
RC001 v_1mod.vi 25 KB -
Could you just look at this vi and tell me if i am doing anything wrong? I get errors that are different each time I change something. here are the inputs I am using
Output Side:
amplitude = 1
freuency = 50kHz
Sampling Frequency = 1MHz
3 of Samples = 200
Input Side:
Input Buffer 4000
trigger type = analog
pretrigger = 5
edge or slope = rising
scan rate = 500kHz
# of scans = 2000
Conditional Retrieval
mode = on
slope = rising
skip count = 0
level = .1
offset = 0
hysteresis = 0
So what we want to do is capture the ten
cycles of the 50k output pulse on the input and need to store that so we can plot it later, do you have any suggestions. we are using the PCI-MIO- 16E board.
Thanks,
Jarrod
Attachments:
InputOutput2.vi 88 KB1) Toss the sequence frames (no flames please).
2) Set you read and have it ready to trigger before oing the output.
3) After the output, go back and read the data that is waiting for you.
4) If you have errors tell us what they are and under what conditions they occured.
End of Ben's suggestions for now.
Ben
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction -
How to synchronize analog input and output from two different USB daq boards
Hi all,
I have two very differnt USB boards the NI USB 6008, which I am using to acquire the data (Analog Input) and a NI USB 9263, it is an Analog Output only board that I am using to deliver a signal (in this case a square pulse). The reason why I am not using the 6008 Analog Ouputs is because I need to deliver negative voltages and need the full +/-10V range.
Looking at similar posts I am pretty sure that I can't use an external trigger or a shared clock, I also tried to use the synchronization of timed structures but no cigar.
I am including a quick vi that I whipped out showing how the signal jitters due to the lack of synchronization. The AO from the 9263 connects to the AI in the 6008 in this example.
Solved!
Go to Solution.
Attachments:
Test Pulse.vi 117 KBI talked to a specialist in the phone and tols me that it is not possible.
-
How to trigger a TTL output with an analog input
Hello,
I have an apparatus for measuring the flame speed of various hydrocarbon/air mixtures. The chamber uses central ignition as the means for igniting the mixture. My goal is to film the ignition process with a high speed Phantom video camera. I control the ignition with an analog output signal from a SCC-68 DAQ. I would like to trigger the camera with the same signal that triggers the ignition sequence. The camera is triggered with one TTL pulse so ideally I would connect the output analog voltage signal to an input analog voltage port that would be used to trigger a counter output that generates one pulse.
I have a sample VI that triggers a digital pulse each time the analog trigger level is met and it works for what I am trying to do but I do not understand how the two channels are connected. I also can't figure out how to make the VI end after just one pulse. In the VI the digital counter is supposedly triggered using the /Dev1/ai/StartTrigger slot on the DAQ but nothing is connected to this slot.
I need to first figure out how to make the output_pulses_on_sine_wave.vi terminate after a single pulse is generated. Then I can try to incorporate it into the VI that I use to control the ignition and measure the temperature and pressure once the mixture is ignited.
John
Attachments:
output_pulses_on_sine_wave.vi 27 KBI am using the USB-6259, sorry for the confusion. I would be nice if I could trigger with an analog signal to the ignition system but it is controlled with a high voltage relay that operates when 12 volts are supplied to it. It really isn't a trigger as much as powering on the high voltage relay. To control it, I have a 12 V supply line that is switched closed using a SCC-RLY module. Could I somehow connect the 12 V supply to one of the buses and use a digital trigger to supply the 12V on command to the high voltage relay?
Thanks for the quick response. -
PID Control - analog input, digital outputs
Hello everyone,
I am trying to use the PID toolkit to convert my existing feedback control system to one using PID or just PI whatever works best. Problem is that the tutorials out there discuss in detail about obtaining Analog inputs and using the PID output to control an analog output. Are there any tutorials that show how I can control my process variable which is an analog input by using the PID output to generate digital outputs?
Basically, what I am doing is controlling the incline of my device with two digital outputs that control two solenoid valves. The angle is calculated from a calibration curve that plots distance sensor voltage with Angle. Any help would be immensely apprecitated. I want to try this out on my own before I post some vi's. Thanks!
V
I may not be perfect, but I'm all I got!That is exactly what I am doing currently. I have error bands specified around the target to make sure that it doesn't oscillate. But, under load conditions such as pulsed load conditions, the device goes out of bounds and the values trigger to correct for it. But, what I need is seemless or atleast seemless correction. Currently what I see is sudden adjustments to the incline. Please find attached what I am currently using. I am trying to get a more finer solution if at all possible.
Note: Within 5% of the target = NO action
Between 5% and 15% = Pulsed ACtion ( DO On for Pulse width time)
Greater than 15% = continuous action until it reaches Pulse band
I may not be perfect, but I'm all I got!
Attachments:
TDML_subElevationControl.vi 41 KB
TDML_subPulsedValveFuntion.vi 16 KB -
Please help with C code to synchronize counter output to analog input
Hi All,
I am using NI DAQ USB-6353 with text-based C code to control it. I would like to send a continuous pulse train from the DAQ to pulse a power supply, which then activates an electron beam producing current to be read by the analog input port of the same DAQ. I would like to keep only the analog samples during the pulse peak and samples of a couple pulse widths right after. I am successfully to generate a pulse train using the sampled clock from a counter output channel, but fail to use the same clock to synchronize the pulse train with the analog input. DAQmxReadAnalogF64 is not called by the static function EveryNCallback set for the analog input task. Am I doing something wrong with the following codes? It would be great if it turns out only I am using the wrong sampled clock name of the counter ("dev1/PFI8") for the analog input. Or is something more fundamental that a counter cannot be sync. with an analog input?
Would someone be able to send me a link to an example in C or C++ or visual basic showing how to synchronize a buffered sample clocked digital pulse train from a counter output channel to an analog input? To simplify the post, the below codes do not include the static functions EveryNCallback and DoneCallBack, but I can send them if needed.
Many thanks in advance for your help,
Thuc Bui
//setting operation parameters
double initDelay = 0.0, freq = 10;
double dutyCycle = 0.0001; //thus pulse width is 10 microsec
unsigned highTicks = 4; //per period
unsigned numSamplesPerPeriod = highTicks / dutyCycle; //40000 samples/period
unsigned lowTicks = numSamplesPerPeriod - highTicks; //per period
unsigned sampleRate = 2*numSamplesPerPeriod*freq; //800000 samples/s
//create counter
TaskHandle counterTask;
int errCode = DAQmxCreateTask("", & counterTask);
errCode = DAQmxCreateCOPulseChanFreq(counterTask, "dev1/ctr0", "",
DAQmx_Val_Hz, DAQmx_Val_Low,
initDelay, freq, dutyCycle);
errCode = DAQmxCfgSampClkTiming(counterTask, "dev1/PFI8", sampleRate, DAQmx_Val_Rising,
DAQmx_Val_ContSamp, numSamplesPerPeriod);
//create analog input
TaskHandle aiTask;
double minVolt = 0.0, maxVolt = 1.0;
errCode = DAQmxCreateAIVoltageChan(aiTask, "dev1/ai0", "", DAQmx_Val_Diff,
minVolt, maxVolt, DAQmx_Val_Volts, "");
unsigned bufferSize = 10* numSamplesPerPeriod;
errCode = DAQmxSetBufInputBufSize(aiTask, bufferSize);
errCode = DAQmxCfgSampClkTiming(aiTask, "dev1/PFI8", sampleRate, DAQmx_Val_Rising, DAQmx_Val_ContSamp, numSamplesPerPeriod);
errCode = DAQmxRegisterEveryNSamplesEvent(aiTask, DAQmx_Val_Acquired_Into_Buffer,
numSamplesPerPeriod, 0, EveryNCallback, 0);
errCode = DAQmxRegisterDoneEvent(aiTask, 0, DoneCallBack, 0)
//start aiTask first
errCode = DAQmxStartTask(aiTask);
//then counterTask
errCode = DAQmxStartTask(counterTask);Hi Xavier,
Thank you very much for getting back to me. I really appreciate it. I followed your advice with the option 2 and simplified my code by using one of the NI C example templates to generate the below codes (also attached). I was able to see the pulses generated with an oscilloscope, and on the same oscilloscope I could see the ouput pulses of the electron beam probe. Unfortunately, the below code via DAQmxReadAnalogF64 reports of no data read from the probe and finally times out. Below is the error message given by this function. I did check the connection of the analog input wires to make sure they were connected to pin 1 (A0+) and 2 (A0-) because I was using the terminal configuration DAQmx_Val_Diff. Do you see any obvious errors I have made in my codes?
Thanks a lot for your help,
Thuc Bui
Task started, waiting for trigger...
Acquired 0 analog samples DAQmx Error: Some or all of the samples requested have not yet been acquired.
To wait for the samples to become available use a longer read timeout or read later in your program. To make the samples available sooner, increase the sample rate. If your task uses a start trigger, make sure that your start trigger is configured correctly. It is also possible that you configured the task for external timing, and no clock was supplied. If this is the case, supply an external clock.
Property: DAQmx_Read_RelativeTo
Corresponding Value: DAQmx_Val_CurrReadPos
Property: DAQmx_Read_Offset
Corresponding Value: 0
Task Name: _unnamedTask<1>
Status Code: -200284
End of program, press Enter key to quit
********************** C Code **************************************************
#include <stdio.h>
#include "NIDAQmx.h"
#include <math.h>
#define DAQmxErrChk(functionCall) { if( DAQmxFailed(error=(functionCall)) ) { goto Error; } }
int main(void) {
int32 error = 0;
char errBuff[2048]={'\0'};
TaskHandle taskHandleDig=0;
TaskHandle taskHandleAna=0;
double timeout=10;
double minVol = -1.0, maxVol = 1.0;
double initDelay = 0.0;
double freq = 10.0;
double pulseWidth = 1.0e-5; //10us
double dutyCycle = pulseWidth * freq;
unsigned hiTicks = 4;
double sampleRate = hiTicks/pulseWidth; //samples/s
unsigned lowTicks = ceil(sampleRate/freq) - hiTicks;
unsigned nSpPeriod = hiTicks + lowTicks;
unsigned numPulses = 1;
unsigned nSpCh = numPulses*nSpPeriod;
double sampleRate2 = ceil(2.0*sampleRate);
unsigned sampleMode = DAQmx_Val_FiniteSamps;
/*********************************************/ /*/ DAQmx Configure Code /*********************************************/
DAQmxErrChk(DAQmxCreateTask("", &taskHandleDig)); DAQmxErrChk(DAQmxCreateTask("", &taskHandleAna));
DAQmxErrChk(DAQmxCreateAIVoltageChan(taskHandleAna, "Dev2/ai0", "", DAQmx_Val_Diff, minVol, maxVol, DAQmx_Val_Volts, ""));
DAQmxErrChk(DAQmxCfgSampClkTiming(taskHandleAna, "/Dev2/Ctr0InternalOutput", sampleRate2, DAQmx_Val_Rising, sampleMode, nSpCh));
DAQmxErrChk(DAQmxCreateCOPulseChanFreq(taskHandleDig, "Dev2/ctr0", "", DAQmx_Val_Hz, DAQmx_Val_Low, initDelay, freq, dutyCycle));
DAQmxErrChk(DAQmxCfgSampClkTiming(taskHandleDig, "/Dev2/PFI12", sampleRate2, DAQmx_Val_Rising, sampleMode, nSpCh));
unsigned bufferSize = nSpCh;
DAQmxErrChk(DAQmxSetBufInputBufSize(taskHandleAna, bufferSize));
DAQmxErrChk(DAQmxSetBufOutputBufSize(taskHandleDig, bufferSize));
/*********************************************/ /*/ DAQmx Write Code /*********************************************/
DAQmxErrChk(DAQmxWriteCtrTicksScalar(taskHandleDig, 0, timeout, hiTicks, lowTicks, NULL));
/*********************************************/ /*/ DAQmx Start Code /*********************************************/
DAQmxErrChk(DAQmxStartTask(taskHandleAna)); DAQmxErrChk(DAQmxStartTask(taskHandleDig));
printf("Task started, waiting for trigger...\n");
/*********************************************/ /*/ DAQmx Read Code /*********************************************/
double* dataAna = new double[nSpCh];
int32 numReadAna = 0;
int errCode = DAQmxReadAnalogF64(taskHandleAna, -1, timeout, DAQmx_Val_GroupByChannel, dataAna, nSpCh, &numReadAna, NULL);
printf("Acquired %d analog samples\n",numReadAna);
if (numReadAna) {
unsigned nPts = (numReadAna < hiTicks)? numReadAna : hiTicks;
for (unsigned n = 0; n < nPts; ++n) {
printf("%6.3f ", dataAna[n]);
printf("\n");
delete [] dataAna;
DAQmxErrChk(errCode);
Error:
if( DAQmxFailed(error) ) DAQmxGetExtendedErrorInfo(errBuff,2048);
if( taskHandleDig!=0 && taskHandleAna!=0 ) {
/*********************************************/ /*/ DAQmx Stop Code /*********************************************/
DAQmxStopTask(taskHandleDig);
DAQmxClearTask(taskHandleDig);
DAQmxStopTask(taskHandleAna);
DAQmxClearTask(taskHandleAna);
if( DAQmxFailed(error) ) printf("DAQmx Error: %s\n",errBuff);
printf("End of program, press Enter key to quit\n");
getchar();
return 0;
Attachments:
Correlated DIO AI_Sample_Clock Dig Start.c 6 KB -
How to combine Digital Output, a delay and Analog Input in a fast loop
I need to develop a process loop that runs at least at 250 Hz that performs a Digital output, than a delay of 50 microseconds and than an analog input of all the channels. All will be done using ATI MIO 64E3 card. Of course, the acquired data will be processed, displayed and saved. The loop will be running for several minutes until user stops it.
The fastest and most precise timing will occur if you use hardware timing. You can apply hardware timing to analog input on the E Series boards, but not the digital lines. Let's focus on the analog input first. Continuous waveform scanning uses a scan clock, which can be the board's internal one or an external one which you apply. If you want to scan all the channels 50 microseconds after a digital rising edge, then you need an external signal to signify that scan clock.
The E Series boards also have 2 counter/timers onboard that you can use for this purpose. You can set up a retriggerable pulse generation operation, where the counter receives a trigger and then on the user specifications, produces a pulse. You can have that route to the analog input scan clock.
The trigger signal for the counter is that digital pulse. As I mentioned earlier, there is no hardware timing for the digital lines on an E Series board. We do have other digital boards (653x family) that have hardware timed operations if precision is important. If you are satisfied with software's resolution (in the milliseconds), then you can call the E Series board digital function in a loop with a software timer. That digital line can route to the counter to act as the trigger.
So, on the programming side, you can have three separate and independent operations in parallel. One is for the digital function to output on that line every so often. Another is for the counter set at the retriggerable pulse generation. The last is for the analog input. I will describe this in terms of LabVIEW, but it can be done in a similar fashion with the NI-DAQ function calls or Measurement Studio.
The digital examples are in the LabVIEW >> Examples >> Daq >> Digital >> E-Series directory. The Generate Retriggerable Pulse example is in the LabVIEW >> Examples >> Daq >> Counters >> DAQ-STC directory. The E Series boards use the DAQ-STC timing chip.
Go to the LabVIEW >> Examples >> Daq >> anlogin >> strmdisk.llb directory and start with the Cont Acq to Spreadsheet File. This shows how to continuously acquire data and stream it to disk while displaying the data on a chart. Streaming to disk is the efficient way to save data while you are acquiring, as it eliminates the overhead of always opening and closing the file through the iterations of the loop. This saves to a file that can be opened by other applications (Excel, Word, etc.), but it is not as fast as writing to a binary file, which must be opened and read back through LabVIEW. However, for your ~250 Hz rate, it should be fine. Then, go to the LabVIEW >> Examples >> Daq >> anlogin >> anlogin.llb and look at the Acquire N Scans -ExtScanClk example. This shows how to apply the scan clock. Here, the AI Start that you saw in the previous example is replaced by 4 VIs (3 AI Clock Config's and the AI Control). Make those changes to the first example and then add a constant 0 to the AI Control parameter for total scans to acquire. That specifies the continuous operation. The File >> VI Properties >> Documentation menu item of the example describes the physical connections.
If you aren't using LabVIEW, use the NI-DAQ User Manual and the NI-DAQ Help file installed on your machine. You can look at your AT E Series User Manual at the http://www.ni.com/manuals pages for more information on the hardware. Also, if you want to route those signals internally on the board, you can find some entries in the KnowledgeBase at the http://www.ni.com/support pages.
Regards,
Geneva L.
Applications Engineering
National Instruments
http://www.ni.com/ask -
Time measurement between counter output my device and analog input
Hello!
I'm trying to measure the time to generate a digital pulse train on the counter output, that goes to a frequency converter that controls a motor. So I think it'd be the best way to wire the output of the frequency converter with an analogue input and make a timestamp before I generate the pulse and a timestamp when I recognize the singal, but I think that wouldn't be a serious measurement ?
What's the best way to measure the time?
kind regards peterhi there
well, there a several ways to do this. the problem with the software - timestamps is the minimal resolution of 1ms. i'd suggest:
- wire a copy of the digital pulse train to an analog input channel
- wire a copy of the frequency converter to another analog input channel
- create an analog input task with the two channels (the sampling rate defines the timing resolution,make sure to acquire enough samples to see the response signal)
- start this task
- send the digital pulse train
to optimize your acquisition you can use another copy of the digital pulse train as a start trigger for your analog acquisition.
-> then you'll see the digital pulse train on one of the analog channels and the frequency output on the other one. both channels have the same time axis with a resolution defined by your sampling rate (~us depending on your hardware). then you can analyze the data.
search the example finder for examples of how to create tasks and triggers.
Best regards
chris
CL(A)Dly bending G-Force with LabVIEW
famous last words: "oh my god, it is full of stars!" -
How can i measure the time between a pulse output and a pulse back on the input?
Llo,
I have a problem i use a ultrsonic sensor, and when i send a pulse out of 4V then a couple of ms i have a pulse back on the input, how can i exactly know how much time there is between the 2 ^pulse??Use the output pulse to trigger a counter in period measuring mode and stop the counter on the return signal (if the input return signal is large enough to reliably trigger a logic circuit). If the signal is not large enough to trigger the counter directly, an external comparator can be used to generate the stop signal.
Another approach is to use two channels of analog input. Feed the output signal to one of them and the return signal to the other channel. The time between outgoing and return pulses can be determined from the sampling rate. If precise timing is required and your AI board does not have simultaneous sampling, you have to account for the inter-channel time as well.
Lynn -
How to get signal from analog input and send it to analog output (real-time)
Hi everyone,
I am doing simple task in Visual C++ and I am using PCI-6221(37 pin).
Basically, I want to send same signal from 'analog input' to 'analog output'
at the same time (almost), to make it real-time application.
Can someone please provide me sample program.
I would appreciate if you could provide me with the good tutorial which explains
step by step everything about programing NI-DAQmx for C/C++.
Best Regards,
Khassan
Solved!
Go to Solution.This is my code in C++, you can optimize it if it looks too messy. This code reads signal from analog input and outputs it through analog output.
To make this code work additional include directories and library directories must be added from NI.
I hope it helps someone.
#include <stdio.h>
#include <conio.h>
#include "NIDAQmx.h"
#include <math.h>
#define DAQmxErrChk(functionCall) { if( DAQmxFailed(error=(functionCall)) ) { goto Error; } }
int main(int argc, char *argv[])
int32 error=0;
TaskHandle taskHandleRead=0,taskHandleWrite=0;
int32 read=0;
float64 dataRead[1000];
char errBuffRead[2048]={'\0'};
char errBuffWrite[2048]={'\0'};
bool32 done=0;
int32 written;
DAQmxErrChk (DAQmxCreateTask("",&taskHandleRead));
DAQmxErrChk (DAQmxCreateAIVoltageChan(taskHandleRead,"Dev1/ai0","",DAQmx_Val_Cfg_Default,-10.0,10.0,DAQmx_Val_Volts,NULL));
DAQmxErrChk (DAQmxCfgSampClkTiming(taskHandleRead,"",100.0,DAQmx_Val_Rising,DAQmx_Val_ContSamps,0));
DAQmxErrChk (DAQmxCreateTask("",&taskHandleWrite));
DAQmxErrChk (DAQmxCreateAOVoltageChan(taskHandleWrite,"Dev1/ao0","",-10.0,10.0,DAQmx_Val_Volts,NULL));
DAQmxErrChk (DAQmxCfgSampClkTiming(taskHandleWrite,"ai/SampleClock",100.0,DAQmx_Val_Rising,DAQmx_Val_ContSamps,1000));
DAQmxErrChk (DAQmxStartTask(taskHandleRead));
DAQmxErrChk (DAQmxStartTask(taskHandleWrite));
while( !done && !_kbhit() )
DAQmxErrChk (DAQmxReadAnalogF64(taskHandleRead,1,10,DAQmx_Val_GroupByScanNumber,dataRead,1000,&read,NULL));
DAQmxErrChk (DAQmxWriteAnalogF64(taskHandleWrite,read,0,10.0,DAQmx_Val_GroupByChannel,dataRead,&written,NULL));
_getch();
Error:
if( DAQmxFailed(error) )
DAQmxGetExtendedErrorInfo(errBuffRead,2048);
DAQmxGetExtendedErrorInfo(errBuffWrite,2048);
if( taskHandleRead!=0 )
DAQmxStopTask(taskHandleRead);
DAQmxClearTask(taskHandleRead);
if( taskHandleWrite!=0 )
DAQmxStopTask(taskHandleWrite);
DAQmxClearTask(taskHandleWrite);
if( DAQmxFailed(error) ){
printf("DAQmx Error: %s\n",errBuffRead);
printf("DAQmx Error: %s\n",errBuffWrite);
printf("End of program, press Enter key to quit\n");
getchar();
return 0; -
Analog Input and Output in One Single VI
I need help in setting both analog input and output in one single VI. How do I assign channels to be either input or output? How do I simultaneously uses both in one single VI with a while loop structure?? Which AO am I suppose to use to obtain signal from the function generator I have built to feed into the DAQCard-1200?? Help!!
Attachments:
Test1.vi 48 KBOne thing you'll need to be aware of is that you will need to DMA lines: one for AI and one for AO. If you don't, then you can configure the DAQCard to do without DMA using the Config VI. But you certainly can do this.
As far as your function generator, you will want to do a buffered analog output. You will write your buffer of points to the buffer, and then tell NI-DAQ how fast to update your analog output channel with these values.
So, you can be reading from AI and checking the AO process in the same while loop. Just make sure you handle the while loop execution (the wait it exits) correctly. This can get tricky when you're doing two types of measurements.
J.R. Allen -
How to use Digital output to turn on sensor for Analog Input?
I am trying to use a digital output to turn on an array of sensors that I then wish to read on 16 analog input lines. I have a 6024E DAQ card. I am planning to take data at 10-20 hz, so not terribly fast, but I will be acquiring for long periods of time (days) so I will be streaming data to disk.
I have a fair bit of experience in Labview basics, but can quickly get out of my depth when I try something new (like this). I have V6.01.
It looks as though the best way might be to do the DO and then a single AI as individual events, then write to disk and continue through the loop. I am puzzled, however, how to keep this cycle on schedule given that I don't know how long it will take to sample 16 channels
, write the data to disk and get back to the starting point... perhaps this is so fast that I don't need to worry about it? The actual timing of the samples (be it 10 or 20 hz) isn't too critical, as long as I can record at what time they were taken... it would be frustrating to find that I was several seconds off after days of data.Hello,
Thank you for contacting National Instruments.
If you are worried about the time of your acquisition being off, then you should associate each voltage measurement with a timestamp. This will allow you to know the exact time at which the sample was taken and you will never be off. You can use the Get Date/Time in Seconds.vi in our while loop with your AI code so that you can read a sample and read the time. You can than log the voltage value and the timestamp to your file.
Regards,
Bill B
Applications Engineer
National Instruments -
I am using PCI 6036E DAQ card, DAQ 6.9.2. , I have not connected to any external device.
When I tested card(in Test Panel of MAX2.2,DAQ 6.9.2) an error appearing �the device is not responding to the base address� � then I pressed Yes, Then TestPanel window appearing�
In analog Input Tag, there is an error �-10805�. This error also appearing when I run the standard analog input samples (use Delphi 6.0).
I tested analog output functions in TestPanel, Delphi Examples, LabView 6.1. There are not error appearing but there is not output signal (using Oscilloscope to see).
Output, Input digital functions are working correctly.
Next I try to foll
ow all the instruntions as recommended:
-Changing TO another slots PCI
-Reinstall Os WinXP,98SE�
-Use another Computer�
But all of the cases are still not working.(the above error still appeared, no output signal)Nvd,
I'm sorry to hear about the problems that you are running into with your DAQCard. I can understand your frustration with the errors that you are seeing. You mention that you have tried to do some troubleshooting, I was wondering if you have tried all the troubleshooting techniques listed in this KnowledgeBase:
http://digital.ni.com/public.nsf/websearch/DCFCDB240788F8D486256D6A00834D80?OpenDocument
If you have tried all of those things, I would suggest one additional thing to try. I would suggest updating your NI-DAQ drivers to version 7.0. These drivers are the newest versions of our Data Acquisition Drivers, and can be downloaded from our website here:
http://digital.ni.com/softlib.nsf/webcategories/85256410006C055586256BBB002C128D?OpenDocument&
node=132060_US
If you have tried all of the above troubleshooting options, please post a detailed description of what you have tried. This may help to clarify what is going wrong.
Jed R.
Applications Engineer
National Instruments
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