multiple input channels with following start task VIs

[af.ra]

Hello everybody

I have this Vi, trying to acquire two input signals. I get the error 50103 which is because of "Concurrently running two or more analog input or analog output tasks".

obviously, I should combine them into one task but here is the problem:

first: I want one of them to be started after the other one. I dont want them to be started atr the same time.. i dont know how to start them sequently on one task..

second: I want to send the pulse from the analog comparison event of the first input signal to the second one. but i dont know how i can do that when im having both channels in one task.

thanks..

[RavensFan]

You can't.  Multiple channels must be in the same task.

What you could do is start the task with both channels, then just ignore the data in the 2nd channel you wanted to start later until the point of time you are ready for it.

---

af.ra wrote:.

second: I want to send the pulse from the analog comparison event of the first input signal to the second one. but i dont know how i can do that when im having both channels in one task.

---

I don't understand what that even means.

[af.ra]

Dear  RavensFan

thank you for your responce

about the second question:

once the trigger condition set up has been met an analog comparison event pulse is output from the analog trigger circuitry and is then available to the AI, AO and Counter Circuitry.

then I need this pulse signal as the source of triggering for acquiring another input singnal I will add to my Vi later . if you look at my VI, i have connected a analog comprison event to the second input channel samle clock,,, i'm not sure if i'm doing the right thing here or not..

what i was trying to do is that i want this vi to show me the output signal of the analog comparison event which carries the information about the times that my trigger settings has occured..

actually, in the second inut channel, i wanted to make a graph that shows me the times that my first signal has crossed zero points. (which is obvious in my trigger setting)

Is there any way i dont have to combine my input signals in one task and get rid of the error?

[af.ra]

sorry,

i think i was explaining wrong..

what i'm trying to do in this vi is that:

in the first line i'm generating a waveform which is going to be the input waveform to my experiment set up.

in the second line i'm trying to trigger the acquired data with the specified settings (finding the zero crossing points of this signal)

the zero crossing points of the first input signal are used to generate trigger pulses as an sampling clock for the second input signal.

(its called frequency sampling method.)

so, if i combine these 2  input channels into one task, how am i gonna be able to do that?

because in one single task, the channels can't have different triggering settings....

thats the problem..

[Daniel_Eduardo]

Hello af.ra, 

Please take a look to the next information on how to acquire data with different types of triggers:

http://www.ni.com/tutorial/4329/en/

Also you can check the example that you can find at LabVIEW. Go to Help > Find Examples > Browse > Hardware Input and Output > DAQmx > Analog Input > Voltage - Continuos Input.

On this example there is a tab were you can find an example on how to trigger you analog input with an anlog trigger.

Regards,

[af.ra]

Dear Daniel..

thanks for your response

actually i know these stuff..

my problem is that i have to combine my 2 input signals into one task because of the error 50103. and when you do that, input channels in the same taskcan not have different triggers with different settings..

if i could have these 2 input channels on 2 different tasks then no problem.. but it gives me the error 50103...

Regards

[Daniel_Eduardo]

af.ra,

You get this error because the cDAQ you are using has only one internal clock. Here you can read about it:

http://digital.ni.com/public.nsf/allkb/485201B647950BF886257537006CEB89

Have you tried what RavensFan suggested?? 

Regards,

[af.ra]

unfortunately that was not the answer to my question, what Ravensfen said...

i think you misunderstood what i am looking for..

thats the question: 

what i'm trying to do in this vi is that:

in the first line i'm generating a waveform which is going to be the input waveform to my experiment set up.

in the second line i'm trying to trigger the acquired data with the specified settings (finding the zero crossing points of this signal)

the zero crossing points of the first input signal are used to generate trigger pulses as an sampling clock for the second input signal.

(its called frequency sampling method.)

so, if i combine these 2  input channels into one task, how am i gonna be able to do that?

because in one single task, the channels can't have different triggering settings....

[Daniel_Eduardo]

Hello af.ra,

Please could you tell me which cDAQ devices and cardsyou are using in your application?  

Regards,

[af.ra]

hello.

my daq device is a "NI PXIe-6124 16-Bit, 4 MS/s Simultaneous Sampling Multifunction DAQ"

and I have a "NI PXIe-10735-Slot 3U PXI Express Chassis with AC - Up to 250 MB/s"

Regards