differents channel in the same daq

[Talo]

Hello to all the people,
I use LabVIEW 8.0 and one DAQ NT-6133 (only one) and I use four the DAQ channel for obtain the voltage signal of 4 sensors. I need to use another channel with a different  configuration (different number of samples, rate, trigger) and obtain the signal of one of this sensor. It is possible???
Because I´m trying to do it using the same device and differences devices for the four and the extra channel and I can´t obtain good results.
The idea is that I can obtain the signal of the extra channel a1´ without stopping the other four channel a1,a2,a3,a4 that it to say I want to obtain the signal output of the channel a1´ each few time (with low frequency) and for obtain the Ubias of this sensor but with stop the other 4 device that have another different trigger but I don´t be able to do it with positive results.
If someone can answer any question or say to me how I can try to do it I would be very thankfull
Best regards
Gonzalo De Francisco.

[devchander]

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 need to use another channel with a different  configuration (different number of samples, rate, trigger) and obtain the signal of one of this sensor. It is possible???

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If it is a hardware timed continuous acquisition ( be it internal or external scan clock) it is not possible.

If you want to do a software timed acquisition, you can configure all the 5 channels in one task and read 4 channels inside one loop at one specified rate and the remaining 1 channel in another loop at different rate ( Note: These will be single point acquisitons. Hence, number of samples / sec, will depend on the loop rate. You could use timed while loops for this)

[Talo]

Thanks devChander,

It is a not continuous acquisition, I want to read the sample of the 4 channel and of the other 1 channel not continuously. Only with the voltage level be more higher ol lower than the different trigger level, then Could I configure the 5 channel in one task but with different trigger level, sample rate, number of sample???

[devchander]

Could I configure the 5 channel in one task but with different trigger level, sample rate, number of sample???

On E and M series boards, its not possible to configure 2 seperate tasks and execute them at the same time, for a single device

But then, I have not extensively used the S series DAQ boards( the one you are using), so I am not sure if you can do this on S series boards

I hope some one else more knowledged on this aspect, will answer

[Tom_W_[DE]]

Hi Gonzalo-

The timing architecture of S Series (in addition to E- and M Series as devchander mentioned) does not allow for unique timing and triggering on per-channel bases.  All channels of a given type (analog input, analog output) must be acquired from with the same timing and triggering characteristics. 

One method you could use would be to sample all channels at the maximum rate required by the application and then decimate data from channels that you would like to sample at reduced or differing rates.  Please provide the timing and triggering characteristics you need for the first 4 channels versus the 5th channel and we may be able to offer some advice or suggestions on a good approach.

Thanks-

[Talo]

Thanks Tom W,

For example the 4 channels with:

sample/rate 1E6

samples 10000

pretrigger sample 1000

trigger level 0.02

The extra 5th channel with:

sample/rate 100

samples 100

pretrigger sample 10

trigger level 0.001

But I also have the next doubt: The idea is obtain the samples of the 4 channel each long time (because the trigger is overpass i.g each 20 hours (reality it is exceed each several days or month)) and without stop this channels adquisition I need to read the other channel each few time for example each 10 or 5 minutes when the other trigger level is exceed.

Thanks again and I wait for your answer

Gonzalo De Francisco

[Johann.Wagner]

Same as http://forums.ni.com/ni/board/message?board.id=280&message.id=2354