Multi-device Synchronization

[Elias Travassos]

Hello,

I have three devices: PXI-4472 for acceleration measurements and PXI-6133 (x2) for voltage measurements. I need to measure voltages from 16 channels (PXI-6133 (X2)), but I've gotta start to acquire these voltages only after that channel 0 (PXI-4472) measure a right level from an acceleration.

Well, I don't know how to synchronize DSA and S-Series devices. Does anyone make something like this? Could you help me?

Thanks.

[Hillman]

Hi Elias,

 The PXI4472 achieves synchronization by sharing a digital trigger from one device and synchronizing all devices to the same clock.This uses the trigger bus.

However, the triggle lines cannot be written to in a way the S Series (PXI 6133) can recieve them. 

The only i think this is possible it use external connections, where the S Series card is the master - but does the 4472 have external connections? i.e. ClkIn smb connector or the Strobe line?

Please let me know, 

Kind Regards,
James.

[Elias Travassos]

Hi Hillman,

Actually, in my application the PXI 4472 device must be the master. The trigger must be done by an accelerometer in channel 0, providing a known voltage signal. After that, the PXI 6133 devices start to measure in all their channels. Considering that PXI 4472 has only one external connection (an accelerometer) and the PXI 6133 devices has 16 external connections for acquiring data. In the other hand, these devices don't have any external connections in between, only the PXI backplane.

Considering that there's no external connection, I just don't know which property to use. Sharing sample clock, start trigger, reference clock, ...

 Thanks

Elias Travassos 

[Brad_K]

Hi Elias,

The PXI-4472 can export a sample clock over the PXI backplane, and it should be suitable for use as an external sample clock for E/M/S Series boards. Try setting the sample clock source on the PXI-6133 tasks to /PXI1SlotN/ai/SampleClock, where PXI1SlotN is the device name of the PXI-4472. You will need to start the PXI-6133 tasks before starting the PXI-4472 task, so that the PXI-6133 boards will be ready to acquire data as soon as the PXI-4472 starts.

Note that this differs from DSA-to-DSA synchronization, which is done by sharing the sample clock timebase, sync pulse, and start trigger.

Brad

[Hillman]

Hi Elias,

Sorry for the confusion.

I have recently delt with HSDIO and an S-Series Card - where the HSDIO could only output on external connections. 

I am very sorry for the inaccurate advice. 

As Brad as correctly pointed out, the trigger lines should be fine. 

Kind Regards,

James. 

[faustina]

I am dealing with the same hardware including an SCXI chassis.  I'm not sure how to apply your suggestion to my implementation. 

I create a task for each high speed card.  All the channels for a card in a single task.  All the SCXI channels are in a single task.

After setting time of sample clocks for all devices (usign DAQmx Timing VI - Sample Clock) I run SyncTasks.vi.  However, I do not use DAQmx Start Task VI to start the tasks, but use Acquire Data.vi.

I have enclosed the 2 VIs mentioned and enclosed a PPT file showing how the hardware is connected in MAX.