How to synchronize two 6133 card for 8 differencial input sampling?

[David_Lin]

Hi,

I have to sample 8 differential channels of high speed signals, so I chose two 6133 cards. I have three questions. 1) What is the highest sampling frequency per channel if 4 differential channels samples simultaneously for the 6133 cards? 2) How to synchronize two cards to start sampling at the same time? Is there any post covering the issue? 3)To realize the syncronization and high speed sampling, is the DAQmx enough? Or I have to use the library in the Lavwindow/CVI?

Thank you very much!

David

[reddog]

1) What is the highest sampling frequency per channel if 4 differential channels samples simultaneously for the 6133 cards?

The 6133 is a simultaneous sampling board with independent ADCs per channel.  This means the per channel sampling frequency isn't impacted by the number of channels you are acquiring.  The 6133 has a max sampling frequency of 3 MS/s.

2) How to synchronize two cards to start sampling at the same time? Is there any post covering the issue?

If you are using NI-DAQmx 8.1 or later, you can use a multi-device task to automatically synchronize AI channels across multiple S Series boards.  To do this, simply use a channel string containing channels from both devices when adding channels to your task (e.g. "Dev1/ai0:3,Dev2/ai0:3").   The driver will then automatically take care of sharing the appropriate trigger and clock lines in order to syncrhonize the two boards.  For this to work, you will first need to go to MAX and identify the appropriate devices as being attached to the same RTSI cable (if using PCI boards) or identify the PXI chassis the devices are in (if using PXI boards).  Without doing this, the driver won't know their is a shared trigger bus it can use to send trigger and clock signals between the two devices.

Also, the 6133 supports up to 8 differential channels so I'm not sure why you need two devices if you only want to acquire 8 channels.

3)To realize the syncronization and high speed sampling, is the DAQmx enough? Or I have to use the library in the Lavwindow/CVI?

I'm not exactly sure what you mean here, but DAQmx should be enough.  If you're using CVI, you shouldn't need to call into any libraries provided by CVI.  If you just want to use straight C through some other environment, DAQmx provides an ANSI C API that you can call into directly.

[David_Lin]

Hi,

Maybe I made a mistake. The info of 6133 says its analog input is '8 SE/8 DI"  and the datasheet says it has 8 analog inputs and I thought it has 8 analog inputs, that is 4 differential inputs. So actually here 8 DI means 8 differential inputs, right? If that's the case, it will save me a lot of trouble.

Also, I noticed there is 64M on-board memory. Is it just for the data buffer? Will I be able to get access to it with DAQmx 8.1?

Thanks a lot for your timely response.

David

[David_Lin]

Hi,

I just confirmed that 6133 has 8 differential inputs. So my question is that can we use the card as either 8 differential inputs or 16 single inputs?

Thank you very much!
David

[Justin_M]

Hi David,

The 6133 can have 8 differential inputs or 8 RSE inputs.  As reddog mentioned above, the S-Series devices have a separate ADCs for each channel.  Because of this, you don't have to use two separate channels to run in differential mode (as you would on an M-Series device, for example).  Take a look at the pinmap on the last page of the manual, linked below:

NI 6132/6133 Specifications

Thanks,

Justin M.

National Instruments