Discussion:
CAN DAQ data synchonization
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jcox
2008-06-19 21:10:07 UTC
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I would like to control position/velocity motion wavefroms of 2 axis over CAN, and need 1 more channel of DAC output for a pressure contol loop that would be synchronized to <<1mS with the motion profiles, ~200-400 points/second, also collect 16 channels of analog in per point, also sync'd to wavefroms
 
could I use USB-8473s and USB-62xx together in a SBC (e-Box 4300?) running Win CE 5/6
 
will these play together?, under Win CE?, with finite code dev time C/C++, possibly .NET ?
 
can I use 62xx master clock and hardwire digital outputs to RTSI on the CAN adapter for time synchronization?
 
any better/easier/more obvious way to do this?
Chris G in AE
2008-06-20 23:10:06 UTC
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Howdy jcox, It sounds like you have a good grasp on what you need to be doing, except our CAN drivers will not work with Windows CE.  Also, most Windows CE devices do not have a USB interface, so I'm curious what your overall application is.  Is there any want to use a different OS? 
jcox
2008-06-21 19:10:06 UTC
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the industrial/embedded control and Single Board Computer worlds are growing together/overlapping

e-box and many other pc104+/epic/mini-itx SBC have desktop PC features at low cost and in nice form factors

there is a zoo of bus interfaces/form factors in this market ? but USB is becoming a ?universal? option on all recent SBC offerings ? and there is good variety in USB DAQ and CAN USB devices/manufacturers



I'm attracted to these new SBC products for real time instrument control and measurement, with minimal local software and cheap USB interface hardware collecting/synchronizing and pushing data to the users desktop PC over ethernet



for this specific project we would like to eliminate servo pots for analog motion monitoring and use CAN motor drives (Copley Accelnet or Xenus) for multiaxis coordinated motion waveforms - monitoring the motion/positions from the CAN PDO/SDO reported motor angles

I see a problem in bridging the multiple clocking domains to keep the DAC controlled pressure waveform and ADC data collection on the DAQ hardware lined up with the CAN controller's idea of time, since the CAN drives would be generating interpolated motion profiles from their internal system time

NI hardware looks like a potential solution but I see that your software/driver model doesn't appear to support small portable drivers for individual devices that would allow easy use of your hardware outside of your software ?ecosystem? - or in "smaller" (< 512MB RAM?) systems

My desire for a cheap, adequate and highly supported RTX with generous high level services leads me to Win CE - and I expected there would be a low threshold for people with Windows driver software to port to CE

the OS needs to be ?real time? enough to keep the Copley CAN motor drive PVT tables that generate the interpolated motion profiles updated without gaps/dropouts over months of operation ? not something I'd expect from XP, also the smaller/cheaper SBC may have ?only? 256MB RAM ? not enough for XP and NI DAQmx

please let me know if I've misunderstood NI's software environment options
Sputnikrent
2008-06-23 21:40:06 UTC
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Hi jcox, Unfortunately, we have not developed CAN drivers for the Windows CE environment, and we do not yet have a driver developer kit released for out NI-CAN devices.
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