Generate 8 train of pulses with different phase shift from 400Hz input reference using PXI-6251.

[John_P1]

Hi kekin,

Unfortunately, the PFI lines don't physically support clocked DIO Waveform operations.  They are used either for static DIO or as lines that let you route timing / triggering signals (including connecting to the on-board counters).  As you have already noticed, there are only 2 counters available on M Series DAQ devices which does not give you enough lines.

Are you open to a hardware addition or replacement? 

Many boards have 32 lines on port 0 (these typically require a second 68-pin connector to connect to the extra 24 HW-timed lines).  Examples of this in PXI form factor are the 6224, 6254, or 6259. 

The lowest cost option for adding an additional 8 HW-timed DO lines to your PXI system is most likely through a second board--i.e. the PXI 6220.  If slot availability or future expansion is a concern, I'd recommend one of the above boards that have 32 clocked DIO lines.

Best Regards,

[John_P1]

Edit:

I just saw Kevin's post and now I am a bit confused of what you are trying to do.  Did you read his caveats and warnings about using an M Series DO task for your application?

Best Regards,

[kekin]

To put the things in simple way, I am trying to generate 8 to 12 different waveforms on PFI lines of 6251. These waveforms will be every time re-triggered by the 400Hz input square wave.

I have following free resources with me. I cannot add more Hardware.

1.One PXI-6509 card whose 68 DIOs are free.

2.One PXI-6251 card whose PORT 2 & 3 are free.(Port 0 already used for some other purpose)

3.One PXI-6723 card whose 32AOUT channes & 9 PFI.2 Counter OUT & 1 FREQ OUT is free.

4.One PXI-6225 card whose 80AIN are free.All ports are used.

With these resources in HAND can I do the waveform generation. I believe only optin left is to use 6723 & generate 5V waveforms using that.But then how should I always re-trigger the wavefors? Also do I have to use PXI triggers here, if i use multiple cards?Can I use 6509 DIOs?

[John_P1]

Hi kekin,

Unfortunately what you have won't work unless you can free up some DO lines.  Of those 4 boards, Only the 6225 and 6251 have clocked DO (available only on port 0).  The 6509 and 6723 have static DO only.

PFI lines cannot generate waveforms, but they can route counter outputs.  Looking at your earlier posts it seems like you just need to generate a single pulse per trigger rather than an arbitrary digital waveform.  The counters would be suitable for this, you just don't have enough of them.  The 6251, 6723, and 6225 all have 2 counters, giving you 6 in total.

You would need to either add new hardware, free up clocked DO lines, or implement external digital circuitry to do what you need.

Best Regards,