Specified route cannot be satisfied for edge counter on Dev1/ai/SampleClockTimebase

[patrick984]

Hi all,

In Record digital sync signal using PFI0/PFI1 I was able to record the arrival time of a digital signal on PFI0 relative to the samples in an Analog Input task by counting the AI task SampleClockTimebaseSource. This all worked fine when using just one of the modules in a cDAQ-9188XT, however when I configure an analog input task to acquire from all of the modules I am now getting:

Error -89137: Specified route cannot be satisfied, because it requires resources that are currently in use by another route.

Property: SampClk.Timebase.Src
Property: SampClk.Timebase.ActiveEdge
Source Device: cDAQ9188XT-18D1D88Mod1
Source Terminal: ai/SampleClockTimebaseHF

My guess is that SampleClockTimebaseSource is being used by the cDAQ to synchronise acquisition between the modules and now it is not available for my counter task. Is there any other way for my counter task to access/share this clock signal?

Cheers,

Pat.

[MajorTom]

Hi Pat,

It appears that you are correct about only one analog input task accessing the sample clock. There are some additional on-board clocks within the cDAQ that you can use for timing. I have included a link that has instructions on how to use these on a cDAQ-9172, but the process should be the same.

http://digital.ni.com/public.nsf/allkb/EEB574335BA0B4EB862572060055E9DD?OpenDocument

[patrick984]

Hi Thomas,

Unfortunately that document does not seem to have any helpful information. I already know how to access _ctr0 and _ctr1 (in fact I am already using both to acquire data off PFI0).

I was hoping to find a way to share the sample clock timebase source (the master 12.8 MHz timebase, presumably from the first AI module). Or if that is not possible is there a way to setup another clock that runs with the same frequency and phase (i.e. synchronously) with the AI timebase clock?

Cheers,

Pat.

[MajorTom]

Hi Patrick,

I found a method to export a sample clock which can be found at this KnowledgeBase Article (http://digital.ni.com/public.nsf/allkb/3A7F1402B2A1CE7686256E93007E66C0). What we are looking at is at the bottom of the article. Using this method we can assign the master clock to a PFI line and then in the slave tasks we can specify that line on the sample clock.

[patrick984]

I get the following error when I click on that link:

HTTP Web Server: Lotus Notes Exception - Entry not found in index

[patrick984]

Found the link, its: http://digital.ni.com/public.nsf/allkb/3A7F1402B2A1CE7686256E93007E66C0?OpenDocument

It appears the "Sample Clock" shown in the example document is the same as the SampClk.Src which I can already access directly using the DAQmx Timing node.

However I cannot find the 12.8 MHz timebase clock in the signals enum for the DAQmx Export Signal VI, and it is the sample clock timebase that I would like to export.

Regards,

Pat.

[MajorTom]

Pat,

Are you able to see that sample clock in MAX under Device Routes?

[patrick984]

Thomas,

I can see /cDAQ9188XT/ai/SampleClockTimebase under MAX->Device Routes but I'm not sure if this is exactly the one I'm after, I put a probe on the output of SampClk.Timebase.Term and ran my code and the output was:

/cDAQ9188XTMod1/ai/SampleClockTimebase (note the Mod1)

I can actually also see this under MAX->Device Routes but I have to select the first NI 9236 module first (in the tree view on the left)

/cDAQ9188XT/ai/SampleClockTimebase has a Direct Route (green cell) to /cDAQ9188XT/ai/SampleClock and all the other cells are empty.

/cDAQ9188XTMod1/ai/SampleClockTimebase appears to have no routes (all cells are empty)

Regards,

Pat.

[MajorTom]

Hey Pat,

I believe what we want to use is /cDAQ9188XT/ai/SampleClockTimebase. Try using that throughout your VI and see if that works.

[patrick984]

Hi Thomas,

If I try to wire /cDAQ9188XT/ai/SampleClockTimebase to my counter I get a different error:

Specified route cannot be satisfied, because the hardware does not support it.

Regards,

Pat.