- From: Tim Holt <holtt_at_nacse.org>
- Date: Wed, 07 Jan 2004 21:09:36 -0800
Oh - Question 2. WHen I run the cmd.c example, my data comes out in "bunches" - like it's buffering up. It seems to buffer up about 3 seconds of data at a time. If i try to set cmd->flags = TRIG_WAKE_EOS it just seems to lock up and nothing happens. In fact I totally lose my ssh terminal connection to my host I'm programming on. Tim Holt wrote: > I've been reworking some code, and started with the demo "cmd.c" code > as a base. First, I extended it to grab 16 channels of data, as I > happed to have a signal generator feeding a sine wave pattern to my > 15th channel. Now here's the odd behaviour: the count numbers, when > they drop to around 2000 or so, seem to wrap and suddenly jump up to > 63,000 or so. Here's a paste of the results... > >> 63430 2291 2900 2657 2070 2070 2070 2071 2070 2070 2069 2070 2071 >> 2069 62789 2071 >> 63429 2373 2564 2632 2070 2069 2070 2071 2070 2070 2070 2070 2071 >> 2070 62883 2072 >> 63429 2421 2391 2621 2070 2070 2070 2071 2070 2069 2070 2070 2070 >> 2070 62981 2072 >> 63429 2461 2357 2611 2070 2069 2070 2071 2070 2070 2070 2070 2071 >> 2070 63085 2071 >> 63430 2581 2362 2586 2070 2070 2070 2070 2070 2069 2070 2070 2071 >> 2070 63193 2072 >> 63430 2660 2368 2574 2070 2069 2070 2071 2070 2069 2069 2070 2071 >> 2070 63303 2072 >> 63430 2678 2373 2575 2070 2069 2070 2070 2070 2070 2070 2071 2071 >> 2070 63415 2072 >> 63429 2668 2395 2590 2070 2069 2070 2071 2070 2069 2070 2070 2071 >> 2070 2087 2072 >> 63429 2659 2409 2600 2070 2069 2070 2071 2070 2070 2070 2070 2070 >> 2070 2198 2072 >> 63430 2655 2424 2600 2070 2070 2070 2070 2070 2070 2069 2070 2070 >> 2069 2309 2072 >> 63429 2653 2496 2589 2070 2069 2070 2071 2071 2070 2070 2070 2070 >> 2069 2416 2072 >> 63430 2651 2554 2581 2070 2070 2070 2071 2070 2069 2070 2070 2070 >> 2069 2521 2072 >> 63430 2648 2570 2578 2070 2070 2070 2071 2070 2069 2070 2070 2070 >> 2070 2620 2072 >> 63429 2575 2580 2573 2070 2070 2070 2070 2071 2070 2069 2070 2071 >> 2069 2713 2072 >> 63429 2474 2590 2567 2070 2070 2070 2071 2070 2069 2070 2070 2070 >> 2069 2800 2072 >> 63429 2431 2595 2565 2070 2070 2070 2071 2070 2070 2070 2070 2071 >> 2070 2879 2071 >> 63429 2331 2660 2561 2070 2070 2070 2071 2070 2070 2070 2071 2070 >> 2070 2950 2072 >> 63429 2163 2755 2556 2070 2070 2070 2070 2070 2070 2070 2071 2070 >> 2069 3011 2072 >> 63429 2088 2792 2554 2070 2070 2070 2070 2071 2070 2070 2070 2071 >> 2070 3061 2072 >> 63429 2210 2718 2564 2070 2070 2070 2071 2071 2070 2070 2070 2071 >> 2070 3098 2072 >> 63429 2519 2567 2583 2070 2069 2070 2071 2071 2070 2070 2070 2071 >> 2070 3120 2071 >> 63429 2675 2498 2590 2070 2069 2070 2071 2071 2069 2070 2070 2071 >> 2070 3132 2072 >> 63430 2718 2472 2577 2070 2069 2070 2071 2071 2070 2070 2071 2071 >> 2069 3136 2071 >> 63429 2753 2439 2546 2070 2069 2070 2070 2071 2070 2069 2070 2070 >> 2070 3134 2072 >> 63429 2772 2422 2532 2070 2069 2070 2071 2070 2069 2070 2070 2071 >> 2070 3125 2072 >> 63430 2773 2443 2547 2069 2070 2070 2070 2070 2070 2070 2070 2071 >> 2070 3106 2072 >> 63429 2757 2521 2594 2070 2069 2070 2071 2070 2069 2070 2070 2071 >> 2070 3074 2071 >> 63429 2746 2568 2620 2070 2069 2070 2070 2071 2069 2070 2071 2071 >> 2070 3027 2072 >> 63429 2741 2537 2613 2070 2069 2070 2071 2070 2069 2070 2071 2071 >> 2070 2969 2072 >> 63429 2735 2347 2567 2070 2070 2071 2070 2070 2070 2070 2070 2070 >> 2069 2900 2072 >> 63430 2730 2217 2539 2070 2069 2070 2070 2071 2069 2070 2070 2071 >> 2069 2822 2072 >> 63430 2725 2214 2537 2070 2070 2070 2071 2070 2069 2070 2070 2070 >> 2070 2737 2072 >> 63430 2687 2422 2562 2070 2070 2070 2071 2070 2070 2070 2070 2070 >> 2069 2645 2072 >> 63429 2651 2591 2581 2070 2070 2070 2071 2070 2070 2070 2070 2071 >> 2070 2545 2072 >> 63429 2644 2632 2583 2070 2070 2070 2070 2070 2070 2070 2070 2071 >> 2069 2441 2071 >> 63430 2697 2568 2574 2070 2070 2070 2071 2071 2069 2070 2070 2071 >> 2070 2333 2071 >> 63429 2757 2501 2567 2070 2069 2070 2071 2071 2070 2070 2070 2070 >> 2070 2223 2071 >> 63429 2775 2479 2564 2070 2070 2070 2071 2070 2069 2070 2070 2071 >> 2070 2111 2072 >> 63429 2690 2472 2568 2070 2070 2069 2070 2071 2069 2070 2070 2070 >> 2070 63437 2072 >> 63430 2569 2467 2571 2070 2070 2070 2071 2070 2070 2070 2070 2071 >> 2070 63324 2072 >> 63429 2524 2467 2572 2070 2070 2070 2071 2070 2069 2070 2070 2071 >> 2070 63213 2072 >> 63429 2608 2495 2568 2070 2069 2070 2071 2070 2069 2070 2070 2071 >> 2069 63104 2071 >> 63429 2765 2536 2562 2070 2070 2070 2071 2070 2069 2069 2071 2070 >> 2070 62999 2071 > > > > You can see how the 2nd from last column suddenly wraps to a high > number when it drops below 2000 or so. > > OK - now clue #2. I can also run the "tut2.c" example and get nice > clean voltages out, which do not do this. Here's some sample output > (of just channel 15)... > >> 000967 -5.27717V >> 001032 -4.95971V >> 001111 -4.57387V >> 001205 -4.11477V >> 001309 -3.60684V >> 001423 -3.05006V >> 001553 -2.41514V >> 001690 -1.74603V >> 001812 -1.15018V >> 001953 -0.461538V >> 002091 0.212454V >> 002231 0.896215V >> 002367 1.56044V >> 002500 2.21001V >> 002625 2.82051V >> 002740 3.38217V >> 002843 3.88523V >> 002936 4.33944V >> 003014 4.72039V >> 003073 5.00855V >> 003111 5.19414V >> 003131 5.29182V >> 003136 5.31624V >> 003132 5.2967V >> 003116 5.21856V >> 003081 5.04762V >> 003025 4.77411V >> 002949 4.40293V >> 002858 3.95849V > > > > Note how when the sample drops below 2000 (or so) that's where we go > to negative voltage. > > What is going on here!?! It's like a sign bit's not right! > > OK now here's the REAL question. I need to be using the > comedi_command() style of DAQ to set up my card to do the timing, > etc. But with comdei_command, it looks like I lose access to all > these nice functions like comedi_get_maxdata(), comedi_get_range() and > most importantly comedi_to_phys(). How can I use the comedi_command() > type of DAQ, use read() to get my data, and still use comedi_to_phys()? > Tim Holt > NACSE > > > _______________________________________________ > comedi mailing list > comedi_at_comedi.org > https://cvs.comedi.org/cgi-bin/mailman/listinfo/comedi
Received on 2004-01-08Z05:09:36