- From: Michael Wouters <Michael.Wouters_at_csiro.au>
- Date: Thu, 7 Nov 2002 15:38:01 +1100 (EST)
I am having problems getting external triggering to work. What I want to do is: (1) start an acquisition using an external trigger (2) collect 512 samples on a single channel, with CONVERT started from an external source It appears that the following should be OK as a command: d->scan.subdev = 0; /* subdevice is ADC */ d->scan.flags =0; d->scan.start_src = TRIG_EXT; d->scan.start_arg = 0; /* PFI0 */ d->scan.scan_begin_src = TRIG_EXT; d->scan.scan_begin_arg = 2; /* PFI2 */ d->scan.convert_src = TRIG_EXT; d->scan.convert_arg = 2; /* PFI2 */ d->scan.scan_end_src = TRIG_COUNT; d->scan.scan_end_arg = 1; d->scan.stop_src = TRIG_COUNT; d->scan.stop_arg = 512; d->scan.chanlist = d->chanlist; d->scan.chanlist_len = 1; and a call to comedi_command_test() says OK but it isn't. In particular (1) When the command is executed, it returns rather more than 512*2 bytes (sometimes hundreds of bytes more) (2) If I disconnect the trigger on PFI0 (acquisition start), acquisition starts anyway, read() never returns 0 and the readout loop sits there forever spitting out readings. (3) Looking at the digitized signal, it appears that the acquisition trigger is occurring at a random time. I had this card doing the same job with Labview+Win95 no problems so it's not a signal problem. Vital statistics comedi 0.7.65 kernel 2.4.19 NI-ATMIO-16E And a related question: in an old post on the mailing list, it was said that the upper two bits of _arg were used for setting triggering parameters( edge/level/rising/falling). This no longer seems to be the case. Is this correct ? If so, how is this functionality accessible ? Cheers Michael Wouters. ---------------------------------- Dr Michael Wouters Time and Frequency Section National Measurement Laboratory CSIRO Division of Telecommunications and Industrial Physics PO Box 218, Lindfield NSW 2070 Sydney, Australia (street address: Bradfield Rd, Lindfield NSW 2070) Phone: (61 2) 9413 7268 Fax (61 2) 9413 7631 ----------------------------------
Received on 2002-11-07Z04:38:01