Acquiring data from two PXI DAQ cards simultaniously.

[Preetam]

I am using LabVIEW 7.0 with DAQ ver. 7.0.

I am using PXI-1000B with two PXI-6070Es.

How can I Acquire data from PXI DAQ cards simultaniously?

[RIO-Todd]

Greetings,

To acquire data from two DAQ cards simultaneously, you can simply run two, separate VIs (one VI for each device) at the same time. For instance, you could open two instances of the NI-DAQmx shipping example within LabVIEW called 'Cont Acq&Graph Voltage-Int Clk VI' and choose physical channels on each device for each VI. For instance, choosing Dev1/ai0 for one VI and Dev2/ai0 for the other VI and running both VIs, you would be acquiring from both devices simultaneously.

If you are wanting to synchronize both devices (have both devices use the same analog input clock), you can do that as well. Search through the LabVIEW shipping examples for the 'Multi-Device Synch-Shared Ext Sample Clk VI.' This VI sychronizes two devices by routing the analog inpu
t clock of one device to the other device through a RTSI line (this would happen through the PXI backplane). This example will show you how to accomplish sychronization with the two DAQ devices.

I hope this helps. Let me know if you have any additional questions. Have a great day.

Regards,

Todd D.
NI Applications Engineer

[ssomnath]

Hi, I need to acquire data from 31 channels simultaneously. We bought two PXIe 6368 boards for this purpose. When I start the task to acquire data, I get an error (see below). Obviously, I cannot use two separate vis to record data since I need to have everything happen simultaneously. Any help here would be greatly appreciated.

Once I saw errors, I removed most of the input channels and just the first analog input from (ai0) from the two 6368 boards.

When I use the OnboardClock I get:

Error -89137 occurred at DAQmx Start Task.vi:5

Possible reason(s):

Specified route cannot be satisfied, because it requires resources that are currently in use by another route.

Property: RefClk.Src
Source Device: PXI1Slot2
Source Terminal: PXIe_Clk100

Required Resources in Use by
Task Name: _unnamedTask<1CE>
Source Device: PXI1Slot2
Source Terminal: None
Destination Device: PXI1Slot2
Destination Terminal: RefClockInternal

Required Resources Also in Use by
Task Name: _unnamedTask<1CF>
Source Device: PXI1Slot2
Source Terminal: None
Destination Device: PXI1Slot2
Destination Terminal: RefClockInternal

Required Resources Also in Use by
Task Name: _unnamedTask<1D0>
Source Device: PXI1Slot2
Source Terminal: None
Destination Device: PXI1Slot2
Destination Terminal: RefClockInternal

Required Resources Also in Use by
Task Name: _unnamedTask<1D1>
Source Device: PXI1Slot2
Source Terminal: None
Destination Device: PXI1Slot2
Destination Terminal: RefClockInternal

If I use any other clock, I get the following error message:

Error -201002 occurred at DAQmx Start Task.vi:5

Sample Clock Rate must match the frequency of the internal timebase specified as the Sample Clock Source.

To use the specified Sample Clock Rate, set the Sample Clock Source to OnboardClock. To use the specified timebase as the Sample Clock, set the Sample Clock Rate to the frequency of that timebase.