Synchronizing signal acquisition on PXI-4472 and PXI-6115 cards

[AndrejK]

Hi Daniel,

I have already found the web site you provided link for but I have some difficulties to execute the proposed solution. Could you prepare me a quick sample? In the attachment is the base vi.

Thanks

[Daniel_L]

Hi AndrejK,

I apologize, but it's our general practice here in the Applications Engineering department not to develop code, the reason being that we have Alliance Partners that do that, and also because of bandwidth limitations.  Perhaps someone else already has a synchronization example for the PXI 4472 and the 4220 already.  Otherwise, I'd encourage you to look at the synchronization examples with E-Series devices to develop your program. 

Thanks for your understanding,

Daniel L.

Applications Engineer

National Instruments

[AndrejK]

Hi David,

I have already done synchronization as stated in examples but with no success. The measured signals are not synchronized - the difference is around 20ms so I’m looking for help.

Thanks for the reply, Regards,

Andrej

[Daniel_L]

Hi Andrej,

Let me refer you to this knowledge base, Synchronization with Dynamic Signal Acquisition (DSA) Products with DAQmx.  This knowledge base links several different examples and methods of synchronizing your DSA product to other DAQ devices. 

In the meantime, I have not yet synchronized a PXI 4472 with a PXI 4220 yet, but have only done this with some standard E Series devices.  However, I will attempt to do so this afternoon just to confirm for you that this can be done.  I'll post a result as soon as I accomplish this. 

Also, there is an example program that uses traditional DAQ if you'd prefer to use that over DAQmx. 

Regards,

Daniel L.

Applications Engineer

National Instruments

[AndrejK]

Hi David,

thanks for the link, I believe that from this knowledge database we already received solution from Éva Porgánszki (Applications Engineer, National Instruments Hungary Kft.) Based on her solution we have done some testing today and there is still some delay between measured signals - see the attached *.vi and diagrams. The *vi is just the testing version so please don't be picky about the design because we quickly modified the base solution with the right acquisition signals. Let me explain what kind of sensors are attached to the cards. On 4472 accelerometer(s) and on the 4220  Full  Wheatstone Bridge strain gauged force sensor.

We are now in the phase where we will check the sensors - especially for the force, because the mentioned delay could also be the property of the sensor.

We have started to use the NI-DAQmx because on NI site http://sine.ni.com/nips/cds/view/p/lang/en/nid/12317 is written that this card is designed to work with the NI-DAQmx drivers. And with the NI-DAQmx the configuration of the device is easier then with the traditional DAQ.

Regards, Andrej

[Daniel_L]

Hi Andrej,

I currently have set up a PXI chassis with the 4472 and 4220 synchronized using the same LabVIEW program (from the aforementioned knowledge base) and it seems to be running correctly.  However, I currently don't have access to a strain gauge input so I can't test at the moment how tight the synchronization is.  You are correct, perhaps this delay that you're seeing is associated with your sensor. 

In order to test synchronization, you would want to send the same signal (such as a sine wave) to both devices, and then overlay the two graphs over each other.  However, this may be more difficult to test than other ordinary analog input devices based on the nature of these devices that we are working with. 

Please keep me updated on how troubleshooting goes with Eva, and I will let you know how things are going here.

Regards,

Daniel L.

Applications Engineer

National Instruments

[Daniel_L]

Hi Andrej,

I just wanted to let you know that I was able to synchronize the two cards to roughly 300 microseconds.  I tested this out by sending the same sine wave to both cards (using bare wires to the analog input of the 4472 and the differential sine signal to S+ and S- of the 4220).  Therefore, I'd think that the 20ms differential that you are seeing is probably related to your sensors. 

Please see the attached screenshots. 

Regards,

Daniel L.

Applications Engineer

National Instruments

[AndrejK]

Dear David,

many thank for the support. As soon we will correctly identified the problem for the delay we'll post it.

Best Regards,

Andrej K.

Senior Researcher

CIMOS