NI4472 configuration : Master - stand alone - external clock ?

[Guest2004]

Hello,

I'm going to use multi daq NI4472 PXI.
I use a custom pxi backplane where there are just the PXI STAR line connected (SLOT 2 to SLOT n),all other signal (PXI TRIG,LBR,LBL etc) are not connected. I want to use a custom board in slot 2 for generating independant timebase for each NI4472 ( Slot 2(LBR0) to slot3(PXI STAR),Slot 2(LBR1) to slot4(PXI STAR)etc).

So is the following configuration is correct(i don't have to use the sync pulse)?
**************
MASTER,STAND alone,NO SYNCHRONISATION (don't listen to RTSI5,don't drive to RTSI5,use external clock) External START TRIG.
**************
Thanks a lot. best regards

[reddog]

In general, there are 3 signals that you need to share in order to synchronize 4472's: sample timebase, synce pulse, and the start trigger. The sample timebase needs to be shared across the PXI Star lines because it is a high frequency signal. It sounds like you already have this covered. The sync pulse and start trigger are generally shared across the PXI Trigger lines and ensure the acquisitions start at the same instant in time without any phase error. Without sharing these two signals, you won't have any guarantee to the degree of synchronization between the acquisitions. However, from your post, it isn't clear whether you just want to provide a different timebase to each 4472 or whether you also need for them to start at the same instant in time. If you don't need them to start at the same time, your current solution should be sufficient. In this case, the devices will generate the sync pulse and start trigger signals internally. If you need them to start at the same time, you will need to connect at least two of the PXI Trigger lines across all of your devices on the backplane in order to share the signals across all devices.

[Benjamin_C]

Hello,

You usually need to share 3 signals to synchronize PXI-4472 boards on a PXI chassis. These are the signals presented by reddog. If you can't share these 3 signals between the devices, it will be difficult to synchronize the acquisition on the different devices.
Please provide us more specific information about what you intend to do. I will be able to help you more.

To have more information about 4472 synchronization, I suggest you to see the following documents :
- The "NI 447x User Manual" page 3-15 :
http://www.ni.com/pdf/manuals/322940c.pdf
- "Synchronization with Dynamic Signal Acquisition (DSA) Products with DAQmx" :
http://digital.ni.com/public.nsf/websearch/A133ED27DF9BCC5986256F2E004BA342?OpenDocument
- "How do I Use LAbVIEW to synchronize Multiple NI 4472 DSA Devices for PXI?" :
http://digital.ni.com/public.nsf/websearch/C86E6F6D8FA29A5686256A9900528DF5?OpenDocument

I hope that it will help you. Best regards.

Benjamin
National Instruments France

[Guest2004]

Merci pour vos reponces. Thanks for you're reply.

Je n'ai pas besoin de synchroniser les cartes entre elles.
J'aimerai savoir s'il etait possible de configurer la NI4472 dans le mode suivant :

Pas de lecture du RTSI5 (sync_pulse)
Pas d'ecriture du RTSI5
Utilisation d'un timebase externe.

Je demande ça car cette config n'apparait pas dans la doc logicielle.

Merci pour votre support technique.

[Benjamin_C]

Bonjour,

Il n'est pas obligatoire de partager le signal de déclenchement (trigger) et l'horloge d'échantillonnage entre les cartes. Vous pouvez effectivement ne partager que la base temps.
Votre configuration me semble donc valide.

Cordialement,

Benjamin
Nationale Instruments France