external master timebase NI9237 châssis NI9174

[Soph']

Bonjour,

J'utilise un module NI 9237 avec un châssis 9174, et j'aimerai utiliser une horloge externe pour l'acquisition.

J'utilise de plus le logiciel LabView. Et je n'ai pas la main sur le logiciel pour changer "horloge interne" en "horloge externe"... 

Dois-je utiliser un module supplémentaire qui dispose d'entrées PFI?

Sur mon châssis j'ai branché également les modules 9211 et 9205.

Puis-je connecter mon 9237 sur un de ses modules pour utiliser leur horloge?

Je n'y comprend pas grand chose mais peut être que quelqu'un pourra m'aider?

Merci d'avance

Cordialement.

[JérémyC]

Hello,

And thank you for posting here. Please post in english on this forum or create your post on the french community. 

Regarding your problem, you can choose an external clock by using "DAQmx Timing (Sample Clock)" ("DAQmx Cadencement (horloge d'échantillonage)" in french) function :

You will be able to choose an external clock by connecting the "clock" ("source" in french) input.

I also suggest you to take a look at the examples given in LabVIEW : Click on "Help->Example Finder" ("Aide->Recherche d'exemples..." in french) and look in the "Hardware I/O->DAQmx->Analog Measurements" ("E/S matérielles->DAQmx->Mesures analogiques" in french) category. The "Cont Acq Strain Samples (with Calibration) - NI 9237.vi" is a example which use the function above but without using an external clock.

All you have to do is connecting your external clock to the input of the "DAQmx Timing (Sample Clock).vi".

Good luck. Regards,

[lvilla]

Hi,

I don't know if this is a follow up to an old thread (maybe inactive) but I have a similar problem.

I have a cDAQ 9185 chassis with a Ni9237 module. The manual for the 9237 states that the lowest possible acquisition rate is… “down to 1.613 kS/s depending on the value of n. When using an external timebase with a frequency other than 12.8 MHz, the NI-9237 has a different set of data rates.”

How can I access other timebases provided by the 9185? I need a 1kS/s. If I try to select an external timebase. If I try to create a NI-DAQmx task for a load cell, when selecting Advanced timing tab, and changing the Sample clock type to external, any timebase or sample clock gives me an error -200414. "Possible reason: Requested sample clock is invalid".

[JérémyC]

Hi,

Regarding the error you're getting, as the NI-9237 module uses Delta-Sigma analog converters, the following KnowledgBase article from the NI website is relevant for you: Error -200414 Requested Sample Clock Source is Invalid in LabVIEW When Trying to Synchronize C Serie...

If you still need help after reading this article and the ones mentioned inside, feel free to create a fresh new post (rather than using this old thread).

Regards,

[lvilla]

Thank you Jérémy,

I'll study on this, and if needed I'll create a new post. I still need to learn where to create a new post 😀

A bientôt !