Multi channel simultaneously

[software enigineer]

Hi!,

I am looking to sample 5 channels on the PCI 6251 every 5secs, simultanously and each has a different signals. Is there a way to do this,how?

TIA

[devchander]

Do you mean 1 sample from each of 5 channels continously, every 5 seconds??

[software enigineer]

Yes, I need to acquire 10 samples from each of the 5 channels simultaneously, every 5 secs.

[Dennis_Knutson]

It's just a matter of providing the correct channel list. Assuming that you are using LabVIEW, it would be something like Dev1/ai0:4 for consectutive channels or Dev1/ai0, Dev1/ai3,Dev1/ai5,Dev1/ai7,Dev1/ai9 for non-consecutive channels. You can easily pick multiple channels with either the DAQ Assistant or the browse option of the physical channel control.

The rest is a matter of setting samples to read and your loop rate.

[software enigineer]

Thanks Dennis,

Will it also work if the channels have different sensor (signals) and different sampling rate? How is the simultaneous sampling set, to acquire data at the same time from all the channels?

TIA.

[devchander]

---

Will it also work if the channels have different sensor (signals) and different sampling rate?

---

Well on your DAQ card, you cannot have an Hardware timed acquisition with different sampling rate for different sensors

Since all your AI channels will be timed to share a single ADC, you will have to sample all channels at a common Sampling rate

---

How is the simultaneous sampling set, to acquire data at the same time from all the channels?

---

Look at Example VI's shipped with LabVIEW FindExamples>>Hardware input and output>> DAQmx>>Analog Measurement>> Voltage folder

Read each VI's Documentation ( found at Menu>> File>>VI properties>> Category: Documentation) to understand how to run it and acquire data

[software enigineer]

Will it also work if the channels have different sensor (signals) and different sampling rate?

---

Well on your DAQ card, you cannot have an Hardware timed acquisition with different sampling rate for different sensors

---

okay , different sampling rate for different sensor is not possible, but is it possible if same sampling rate is set for different sensor(acquiring different signals)? If so how?

Thanks

[Dennis_Knutson]

You might want to start by going to http://zone.ni.com/devzone/cda/tut/p/id/5434 and get an introduction to DAQmx.

Put simply, you have a DAQmx function called Create Virtual Channel. You can use this to specify a channel or list of channels to be scanned. If you are mixing sensors (i.e. voltage and temperature), you use multiple Create Virtual Channel functions. The function creates a task and you wire the task output of one DAQmx function to the task input of the next DAQmx function. There is also a DAQmx function called DAQmx Timing. One of the inputs to this is a sample rate (number of scans/second). Look at the shipping examples to see how all of these functions are used.

You also have the option of using the DAQ Assistant. When you start it, you are asked for the type of task (voltage in, voltage out, etc.). You pick one and select the channels. This will create a task. When the creation is done, you can add additonal channels for a different type of measurement. This is all explained in the help text that is displayed by the DAQ Assistant.

[software enigineer]

Thanks to All,

That helps 🙂