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Member
Edmi0
Posts: 27
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Accepted Solution

USB-6212 External Clock Acquisition

Hello Everyone,

 

I'm using a USB-6212 acquistion board and trying to get a digital signal with a determined frequency. I intended to supply the daq with a 4kHz clock, in order to increase my resolution, given the digital lines don't have an internal clock. However, when I try to configure a continuous acquisition with an external clock source in SignalExpress 5, I get a message stating this is not supported.

 

"Requested value is not a supported value for this property. The property value may be invalid because it conflicts with another property."

 

My desired signal is connected to P0.4 and my clock source to PFI0.


Can anyone give a hint on this?

 

Best Regards,

Member
bpracek
Posts: 147

Re: USB-6212 External Clock Acquisition

Hello!!!

The problem is that this board only supports software timing for digital I/Os. As you can see at the specification here:

http://sine.ni.com/nips/cds/view/p/lang/en/nid/207096

The hardware timing is avaiable just on the analog channels.

Hope this helps!

If you have any doubts let us know!

Regards,

Barbara Pracek
Engenharia de Aplicações
National Instruments Brasil

Member
Edmi0
Posts: 27
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Re: USB-6212 External Clock Acquisition

Thank you for your reply,

 

I checked some other hardware that has an internal clock in the digital inputs as well, however it is stated that only 24 out of 32 inputs are timed (USB-6343) or 8 out of 24 (USB-6341). Does that mean that I will be able to perform what I intend on this timed lines, leaving the rest of them useless?

Member
bpracek
Posts: 147
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Re: USB-6212 External Clock Acquisition

Hello!

 

Doesn't mean that this port will be useless...

As the description of the board said, it is a Multifunction Data Acquisition Board, so it allow you performa many types of measures.

So you can use these ports to perform other functions in your system.

 

Regards,

Barbara Pracek
Engenharia de Aplicações
National Instruments Brasil

Member
Edmi0
Posts: 27
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Re: USB-6212 External Clock Acquisition

Definitely, I expressed myself badly, you're 100% right.

 

Thank you for your quick answer

Member
Edmi0
Posts: 27
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Re: USB-6212 External Clock Acquisition

Let's supose I get a X-series daq with timing in the digital lines. Is it possible to have a task with the timed inputs and other task with the regular lines?

 

Thanks in advance.

Member
bpracek
Posts: 147
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Re: USB-6212 External Clock Acquisition

Hi!!!

 

The answer is yes, you can use the other lines. :smileywink:

 

Regards,

Barbara Pracek
Engenharia de Aplicações
National Instruments Brasil

Member
Edmi0
Posts: 27
0 Kudos

Re: USB-6212 External Clock Acquisition

But running them concurrently won't generate errors such as "reserved device"?

For instance, with my current board, I'd have to program some synchronization in order to have two analog input tasks with different sample rates. I could figure this is related to the fact that there is only one sample clock on the hardware.

I just wanted to make sure this won't happen.

 

Thank you for your quick response

Member
bpracek
Posts: 147
0 Kudos

Re: USB-6212 External Clock Acquisition

Hi!!!

This probably occur with your current board, because it don't support simultaneous sampling for analog channels, that means, there is just one ADC converter, so it can't be use by two channels at the same time.

This type of error will always occur when the same resource is requested by two tasks at the same time.

In your case, for instance, it can happen when you try to configure two different clock rates for the digital lines. It isn't possible because the hardware timed lines share the same clock.

Regards,

Barbara Pracek
Engenharia de Aplicações
National Instruments Brasil