unable to acquire data w/ >4 6133 digitizer cards

[Jeff P]

I have been using labview to acquire 32 channels of data on 4 - 6133 digitizer cards for a while now.  I am trying to expand that to 64 channels on 8 - 6133 digitizer cards.  I am triggering off of PFI0 for each card individually.  When I try to acquire data from 5 or more cards at once, there is usually at least on card that fails to trigger after the first pulse. 

[mallorim]

Hi Jeff,

If I understand your issue, you have been able to successfully trigger and acquire 32 analog inputs with four 6133 cards. I am assuming that these are PXI cards. When you try and expand your acquisition to include 64 channels, or eight cards, and you send the start trigger, one of the cards will fail to start.  Is my understanding correct?

Some Questions for further clarification:

1.     What PXI Chassis are you using?

2.     Is it a random card that fails to trigger or always a card in the same slot? When you try all eight cards, is it only one card that fails to trigger or multiple cards?

3.     Could you clarify what you meant when you said that you are “triggering off of PFI0 for each card individually.” Does each card have a trigger wired to its PFI0, or are you trying to synchronize the cards by using the same trigger?

4.     How have you programmed this in LabVIEW? Are the devices synchronized?

Now to address some of these options:

If it is always the same slot that fails to trigger, you may need to bridge between two PCI buses in the backplane of your chassis. Some PXI chassis are multisegmented, or they have multiple independent PCI buses for a group of slots. The Knowledge Base Document 32GFMIWD: Routing PXI Trigger Lines Across the Buses of Multisegment PXI Cha... has a very good explanation of this issue and how to address it. Another possibility could be a damaged board. If you change which 6133 card is in this slot, you will be able to isolate if it is the slot or the card.

If you are using one card to trigger the acquisition on the rest of the cards, you will need to make sure that the listening devices’ tasks are started before the master device.

Thanks, Mallori M.

[Jeff P]

1.) I am using a PXI-52022 Chassis from Chroma ATE.

2.) It is a random card that fails to trigger.  Usually if I send the trigger signal twice, the system will trigger.  But I cannot do that under normal operation or the system will not synchronize.

3.)  Each card has the trigger wired to its PFI0.  This is done through daisy chained BNC connections on the breakout boxes.

4.)  I programmed it setting up the device wizard for each card.  Basically I have 8 device wizards running to handle the 8 cards.

[mallorim]

Hi Jeff,

From the description, it sounds like the trigger may be becoming degraded across all the connections. It is not necessary to connect the trigger to each card individually. I would suggest only triggering the first 6133 card and then using the DAQmx Export Signal.vi in LabVIEW to export the signal to the PXI Chassis’s backplane, preferably on the STAR line or on a PFI line. Then the other 6133 cards could be triggered off that line in the backplane. The Export Signal.vi can be found on the Functions Palette by navigating to the Measurement I/O menu>> NI-DAQmx>> Task Config/Ctrl>> Daqmx Signals>> DAQmx Export Signal.vi.

In your previous post, under answer 4, you mentioned that you were using 8 device wizards. I am unsure here of what you are referring to. Could you have meant the DAQ Assistant? If so, you cannot synchronize multiple DAQ Assistants.

It sounds like you are going through a lot of effort to synchronize one analog input that uses the 8 devices. For you purposes, since you are using S-series devices, synchronization can be relatively easy.

A single analog input task (as seen in the example program Cont Acq&Graph Voltage-Ext Clk- Dig Start.vi) will allow you to include channels from multiple S Series devices. When you include channels from multiple S Series devices in one task, the NI-DAQmx driver will automatically synchronize the devices. The devices must all be in a single chassis, and you must identify the chassis in MAX. With this method, you would also only need one trigger, whose source you could specify and which would trigger the read for all the devices. The necessary syntax to write into the Physcal Channels Control on the example programs front panel is “Dev1/ai0:7, Dev2/ai0:7, Dev3/ai0:7…” where Dev1 is the name in MAX of the card in slot 1, etc.

Regards, Mallori M.