synchronization of two PCI 6602 using RTSI cable and traditional ni-daq

[pchemjjang]

Thank you Doug.

Actually one of the reasons I am trying to synchronize two PCI 6602 cards is because I want to use 4 DMA channels.

Do you know by any chance if there is any counter/timer card that has 4 or more DMA channels?

Thank you very much again for your help.

pchemjjang

[Doug_L._Bear]

The best we have is 3 DMA channels on the 6624.  http://sine.ni.com/nips/cds/view/p/lang/en/nid/12501

[Paul_C.]

Hello pchemjjang,

I was reading through this post and I wanted to mention that we just release our new X series DAQ cards which have four available counters.  These devices also have enough DMA channels to handle each task (you will have a DMA channel for each counter).  This would alleviate you having to synchronize two 6602 cards.

From the way it sounds, you are just starting out a new application with the 6602.  If you are using a version of LabVIEW supported, I would highly recommend using the newer DAQmx driver over Traditional DAQ.  This makes things quite a bit easier regarding synchronization of two 6602s.  If you have two 6602s and a RTSI cable, DAQmx makes routing signals easier by automatically routing them across a RTSI cable for you.  For example, you can specify the 6602 timebasesrc on one device to be the timebase of the other 6602 and all of the routes are handled for you.  Please let us know if you have any additional questions on how to get your program up and running or if you would like to know more about a DAQmx solution.

Regards,

Paul C.

Message Edited by Paul C. on 08-10-2009 04:06 PM

[pchemjjang]

Thank you for your message, Paul.

I need 4 DMA channels and additional 4 counters for pulse generations (these don't have to be DMA, however). Including 2 more counters for timer and trigger, I need total 10 counters, 4 of whcih should be DMA channels as mentioned already.

So I am afraid that the new card with 4 counters won't help me much.

About using DAQmx, however, I have been asked many times already. I just do not have a knowledge at this point and don't know how to convert everything from Traditional DAQ to DAQmx. I was hoping to find out, however, if it is possible to change just a few subVIs from Traditional DAQ to DAQmx, which results in a mix of subVIs written in DAQmx and those written in Traditional DAQ.

I think someone told me that it is not possible to mix the Traditional DAQ and DAQmx in the same VI.

But can I use them in different VIs and somehow mix them or link them together?

I know it sounds crazy, but since people are suggesting using DAQmx, but I have this huge program already written in Traditional DAQ, and I just hope that I can add a few subVIs written in DAQmx if possible.

Thanks for your help and suggestion in advance.

pchemjjang

[Paul_C.]

Hello pchemjjang,

Regarding using DAQmx and Traditional DAQ at the same time.  Only one driver can be used at a time to control a single device.  This means that if you programmed all tasks regarding the 6602's with DAQmx, you can use DAQmx for the 6602's and Traditional DAQ for other devices in the system.  I only made the recommendation because I thought this was a new application and I wanted to recommend you use our latest driver.  If you would like more information on using the DAQmx driver, I would highly recommend taking a look at the article here.  The article does a great job of explaining some of the differences between the two drivers and shows several examples for different task types.

If you plan on using Traditional DAQ, please let us know if you have any difficulty implementing the previously mentioned solution regarding the route signals vi.

Regards,

Paul C.

[pchemjjang]

Hi Paul,

I am trying to synchronize the digital outputs on two 6602 cards using a RTSI cable. Does that mean that I can only use DIO config and other relevant Vi's instead of AI config and Route Signal.Vi?

Thanks for your help in advance.

pchemjjang

[Paul_C.]

Hello Pchemjjang,

The route signal vi can be used, but not the AI config.  You will need to configure the digital lines using the DIO palette with the DIO config and use the route signals vi to export the sample clock, start trigger, etc. across the RTSI bus between the two devices.

Regards,

Paul C.

[pchemjjang]

Hi Paul, 

Thank you for your answer.

In fact, I talked to Jeff (from National Instrument Tech Support) today about this problem.

I guess I need to explain what I am trying to do more clearly.

I am doing buffered event counting and try to use DMA channels.

I have 4 detectors and thus I need 4 DMA channels.

Since a PCI-6602 card has three DMA channels only, I want to use two PCI-6602 cards and synchronize them.

When I looked at an example (which can be found in this thread) about synchronization of NI cards using DIO configs, I noticed that:

1. There is no route signal vi used.

2. DIO read and DIO buffer etc. are being used.

Does that mean that I am supposed to do the buffered event counting using these DIO's?

Or Can I still use the counters of two PCI-6602 (total 4 DMA channels) synchronized through RTSI?

I really appreciate your help.

Regards,

pchemjjang

[Paul_C.]

Hello Pchemjjang,

DIO Read and DIO Buffer are used for digital input / output tasks.  What you want to use is the two available counter lines on the card.  These are programmed with the counter palette.  If you are doing buffered edge counts, there is no need to synchronize the two cards using RTSI except to have them start at the same time.  

The counters will inherently count the edges of your incomming signal as soon as they arrive.   The total count on the counter is read at each sample clock edge.  As long as both cards are provided the same sample clock, they will be synchronized.  The only thing you have to ensure is that they start at the same time.  

After talking with Jeff, it sounds like you are trying to sense photons from a laser.  If this is true, you can simply start all four counter tasks (2 on each board) prior to starting the laser.  Then, by supplying the same sample clock to these counters, each total count will be synchronized to the same sample clock edge.

I've talked with Jeff and he should be able to help you set this up over the phone.  Please let me know if you have any additional questions.

Regards,

Paul C.

Message Edited by Paul C. on 09-04-2009 09:56 AM

[pchemjjang]

Thanks, Paul.

As I explained to Jeff over the phone last Friday, my application is not quite the same as what you might think.

I, however, think that your suggestion can still be applied to my application.

As you stated in your reply, "...supplying the same sample clock to these counters, each total count will be synchronized to the same sample clock edge...", I understand that starting the four counters from two different PCI-6602 cards (two from each card) at the same time is the key.

So as long as I can start the four counters at the same time, I think it will be OK.

But I cannot see how to supply the same clock to the counters on two different boards without using a RTSI cable or PFIs connected with a wire (as Jeff suggested).

I really appreciate your help.

Regards,

pchemjjang