pxi multi-device Synchronization

[crimolvic]

Hello all,

I have some experience in LabVIEW programming, but none in the DAQ field, that´s why I ask you for some help/advices

I have the following issue:

I need to control the aquisition of a PXI DAQ system with one (1) 4461, one (1) 4472 and one (6250) boards. I need this system to aquire the following signals simultaneously:

- Accelerometer signals (4472 and 4461) at the same rate
- Voltage signals (6250) at higher rate
- Tacho TTL signal (with one of the counters of the 6250)

As far as I know, I have to install the 4461 board in slot 2 of PXI. I also have to pay attention to the filter delay between the 4472 and 4461 in order to correct it once the acquisition is made.

But, centering on the programming:
My idea is to create a task for the 4472, another for the 4461 and two for the 6250 (one for voltage input and the other one for the counter).  Am I right by doing this? I am attaching the code that creates the tasks in MAX (run TOPCreateTask.vi). I don´t know if the timing is OK for the counter or should I choose "Implizit" mode.

If yes, then come the second step, which is the synchronization between the boards, being the 4461 the master device. I think that I have to share the Sample Clock Timebase, Sync Pulse and Start Trigger signals between the devices, but I don´t know how to do this. could anyone help me in this issue?

As next step, I think I need to start the devices, starting from the slaves and finally the master device. Is that correct?

Thanking in Advance,

CJMV

[crimolvic]

Please download this code, the previous had an error.

PS: sorry, I didn´t found the edit option

[crimolvic]

no-one?

[crimolvic]

Well I have done some tries on the sinchronization issue, based on some examples and some things found in the developer zone from NI site.

I am attaching the code which has a description of the different steps that I took.

Unfortunately my vi doesn´t run, the error code that I get is: -200077 with a description which says that the desired value is not supported.

Attribute: Sample Clock Source
Requested: /PXI1Slot2/PXI_Star0
Possible selection: OnboardClock

Can anyone tell me what I am doing wrong?

Just as information:
- at the moment I am working with simulated devices in MAX.
- at the moment I am not including the Counter task.

Thanking in advance,
CJMV

Message Edited by crimolvic on 04-25-2007 10:47 AM

[crimolvic]

sorry, I forgot to attach the file

[Elmar_NI]

Hello CJMV,

the reason for the error message is that the 4472 module can not perform a single point acquisition.

http://digital.ni.com/public.nsf/websearch/646923E815076E148625705400686190?OpenDocument

Kind regards,

Elmar

[crimolvic]

Hello,

Here can you find what I have made until now.

I am synchronizing the 4461 and 4472b by sharing the Timebase of the 4461. On the other hand, I am synchronizing the 4461 and 6250 through the PXI_Clk10 Reference Clock.
Before starting the tasks on the slave boards, I am using the Start trigger of the 4461, in this way the three boards starts the acquisition simultaneously.

I can use different sampling rate for each board, however I try to keep the SamplingRate/BlockSizeToRead ratio equal.

can you give me your comments? Is OK what I have done?

greetings,
cjmv

[Elmar_NI]

Hello CJMV,

i could not found a clear error in your program. But you can delete the sequence structure.
Because you are able to define the execution order with the error wire.

Kind regards,

Elmar