Count Onboard Clock

[jstarustka]

I am using the PXI-5671 Upconverter which has a 10MHz reference clock. I have exported that clock and would like to count it. Off of that count I would like to trigger another device.  First, is it possible to count the onboard reference clock and then trigger another device off of that count.  If it is possible could someone please point me in the direction of some vi's that illustrate this?

Thanks

Joe

[Paul_C.]

Hi Joe,

As I understand it, it sounds like what you want is to take the 10MHz reference clock from the 5671 and export it to be used as a reference clock for another device.  When used as a reference clock, it is possible to set your sample clock as a divided down amount of that reference clock.  For example, if you wanted to trigger off a 100KHz signal from 10MHz reference clock you would need to divide it down by 100.  What device are you trying to export the signal too?  Is it another National Instruments modular instrument or one of our DAQ cards?  What type of task are you going to be using with the trigger signal (Analog input, analog output, digital I/O, counter input, counter output, etc)?  If you're looking for examples, I would highly recommend taking a look at our shipping examples if you haven't already.  These can be found in LabVIEW by going to Help » Find Examples.  I would specifically look into the section under Hardware Input and Output » DAQmx (if your using a DAQmx based card).  The examples for our modular instruments can be found under Hardware Input and Output » Modular Instruments.  There are various examples that show how to do aquisition with an external reference clock that you may want to take a look at.  Please let me know if I misunderstood your application or if you need additional help.

I hope this helps,
Paul C.

[jstarustka]

Thanks Paul, I will take a look at those examples. I am trying to trigger two devices, first I want to count the onboard clock and then off that count trigger the PXI-5610 to transmit a waveform.  I then want to export that clock to the PXI-5600 and also count the clock in order to trigger the device to receive the signal. I am working on reproducing a TDMA frame structure and the only clock I have to use is the onboard clock that is built in to the two devices I mentioned.  Now that you know more about what I am doing, is this achievable using the onboard clock.

Thanks

Joe

[Yardov]

Hello Joe,

Are you trying to acquire what you generated here? I am probably not understanding why you want to use the reference clock and not marker signals. Could you elaborate your current challenge description a little more?

[jstarustka]

Hello Gerardo,

I am trying to reproduce a TDMA slot and frame structure.  The TDMA frame I am working on has 1 simplex, 4 uplink and 4 downlink slots with different length guard times between each slot.  I need to transmit a 8.28ms burst every 90ms on one of the 4 downlink slots with the PXI-5610 to a device which will decode process and reply in the next TDMA 90ms frame to my PXI-5600 on one of the 4 uplink slots. The PXI-5600 will decode and process the signal, it is then passed to some code that will form a reply which is again sent out by the PXI-5610 on one of the 4 downlink slots. This process will be continuous. I have already created the vi's used to transmit and receive the bursts and now I need to set up the timing between them.

My idea is to use the onboard reference clock to trigger the PXI-5610 to transmit and then to trigger the PXI-5600 to receive the signal in the next 90ms frame, to do this though I have to either count or divide down the clock. I am just unsure on how to do this. The reason I am looking at the onboard clock is because that is the only clock I have.  If achieving this timing structure would be easier by buying more equipment please let me know and I will contact our sales person, just give me a model number.

Again as always thanks for your help.

Joe  

[Yardov]

Hello Joe,

Thank you for the explanation, it now makes much more sense.

Yes we can use the reference clock but any division of the clock will require extra hardware. Mi initial assessment would be to use your 544x (part of the 567x). If you are doing what we talk about on that forum, you can generate a marker event once your first 4 generation frames finished. This will trigger the acquisition.

The only problem I see here is your external device might need also a sync signal. You can have a second marker event at the beginning of the generation and send this on a PFI line. I attached this image:

If you prefer to use the reference clock, you can divide it down with a 660x card or a 665x card.

Hope this helps,

Message Edited by Yardov on 09-14-2007 02:58 PM

[jstarustka]

Thanks Gerardo,

I have been so focused on a clock that I did not think about using a marker event until you mentioned it in a previous posting.  I set one up and it works perfectly.

Thanks

Joe