On Wed, 13 Mar 2013 16:45:06 -0700 (PDT), the renowned George Herold <gherold@teachspin.com> wrote:> >Hmm, Labjack as an answer to NI. We're always getting requests, to >make Labview, NI 'compatible' apparatus/ experiments. The price tag >scares me... and then labview changes every three years or so. > >George H.I'm afraid it's going to be necessary to be a serious player, it's becoming a standard. Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
PC Data Acquisition
Started by ●March 13, 2013
Reply by ●March 13, 20132013-03-13
Reply by ●March 13, 20132013-03-13
On Mar 13, 7:28�pm, Tim Wescott <t...@seemywebsite.com> wrote:> On Wed, 13 Mar 2013 16:26:15 -0700, George Herold wrote: > > Tim, Can I ask how you plan to deal with the long data files? > > > George H. > > Scilab will happily slurp up multi-megabyte files and process them. �If > it starts having problems I can read the file in manageable-sized chunks. > > -- > My liberal friends think I'm a conservative kook. > My conservative friends think I'm a liberal kook. > Why am I not happy that they have found common ground? > > Tim Wescott, Communications, Control, Circuits & Softwarehttp://www.wescottdesign.comScilab, thanks. I think I even have that on my 'puter at work. (I only played a little.) I can generate these long data files, I was thinking of just writing my own basic program to sort 'em. George H.
Reply by ●March 13, 20132013-03-13
Tim Wescott wrote:> On Wed, 13 Mar 2013 16:26:15 -0700, George Herold wrote: > >> Tim, Can I ask how you plan to deal with the long data files? >> >> George H. > > Scilab will happily slurp up multi-megabyte files and process them. If > it starts having problems I can read the file in manageable-sized chunks. >Consider storing in chunks. There is always that chance that the computer croaks in the middle of the game and then at least you have some data. The usual, Leroy plugging in the big floor buffer machine ... tsk ... KATCHOCK ... light out. -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●March 13, 20132013-03-13
On Mar 13, 8:13�pm, Spehro Pefhany <speffS...@interlogDOTyou.knowwhat> wrote:> On Wed, 13 Mar 2013 16:45:06 -0700 (PDT), the renowned George Herold > > <gher...@teachspin.com> wrote: > > >Hmm, Labjack as an answer to NI. �We're always getting requests, to > >make Labview, NI 'compatible' apparatus/ experiments. The price tag > >scares me... and then labview changes every three years or so. > > >George H. > > I'm afraid it's going to be necessary to be a serious player, it's > becoming a standard.Grumble...> > Best regards, > Spehro Pefhany > -- > "it's the network..." � � � � � � � � � � � � �"The Journey is the reward" > sp...@interlog.com � � � � � � Info for manufacturers:http://www.trexon.com > Embedded software/hardware/analog �Info for designers: �http://www.speff.com
Reply by ●March 13, 20132013-03-13
On 3/13/2013 6:54 PM, Joerg wrote:> Phil Hobbs wrote: > > [...] > >>> >> LabJack comes with C bindings as well as Python. I'm currently using a >> U6 Pro to run a prototype spectrometer. >> > > But IIRC you have a son who can write the C code. I don't, so I have to > use the pre-cooked SCADA stuff. >Nah, he isn't entirely up to speed yet. This is for a spectrometer prototype--very lightweight on the back end stuff--so I'm just going write some simple console-mode thing. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 USA +1 845 480 2058 hobbs at electrooptical dot net http://electrooptical.net
Reply by ●March 13, 20132013-03-13
[quote] "Jamie" wrote in message news:Kr80t.148685$wI7.44946@newsfe15.iad... Tim Wescott wrote:> On Wed, 13 Mar 2013 18:11:17 -0500, Jamie wrote: > > >>Tim Wescott wrote: >> >>>This is slightly OT for all the groups I'm posting to, but something >>>many of you should have done. >>> >>>I have a need to sample one channel of data at between 200 and 2000 >>>samples per second, 12 bits or so, and store it away. >>> >>>The signal happens to be on a 4-40mA line already, to make life easy >>>for getting off-the-shelf hardware. >>> >>>I need to store hours of guaranteed-uninterrupted data, or failing >>>that, store data that's timestamped at the measuring device (not just >>>in the PC software) so that I can see what's missing and deal with it. >>>(dropouts of even a half second or so would be OK, as long as the >>>timestamps are correct). >>> >>>The mental model I'm carrying around is a laptop PC, connected to some >>>little box via USB, quietly buzzing away in a corner making multi- >>>megabyte files with the information I want. >>> >>>I assume that this is a no-brainer with National Instruments hardware >>>and software -- am I correct? If not, is there a solution that you can >>>recommend? Do you have a favorite other than NI? >>> >>>TIA. >>> >> >>I did a hack a few years ago using the sound card. I used an audio >>oscillator that got past into a circuit where the amplitude was biased >>via the signal I was monitoring, mostly less than 24 volts. >> >> I wrote software to capture this sine wave using a basic zero >>crossing detection and calculate amplitude per sample division I wanted >>to know about. The sound card was set to 44k @ 16 bit mode. >> >> With today's PC's, it's common to get 192k sampling rates. >> >> The reason I did the AM coupling method is due to most sound >>cards blocking DC. >> >> THis was done on an old Toshiba Pro with windows 2000. >> >> Of course, you need to write software and build a interface. > > > I left out the part this being something to recommend to a customer to > make measurements and send to me. So hours spent messing around with it > cost $; this is a case where money up front that saves time and effort > saves money in the end. >http://www.dataq.com/products/hardware/di710.htm We have used this produce before... It works well but, you have to make sure you twisted pairs because with some issues with noise, but it worked fine.. Software came it and loads in XP just fine. I used my little Acer with a short network cable. If does sample fast and you do need to have the PC connected to it gathering data at long periods. Jamie [/quote] +1 on dataq. They used to have a $10 or $15 starter kit that did 4 channels at 8 bits up to 200hz, I've used it with their windaq software to log for a day or two at a time with no missing data that I ever noticed. The DI155 has various input ranges, 13 bits, and up to 10 kHz sampling rate. They even offer a $0.99 precision 250 ohm resistor for 4-20 mA current loop logging http://www.dataq.com/products/startkit/di155.htm for info and a link to a primer on logging 4-20 mA current loops :-) (http://www.dataq.com/4-20ma-current-loop-data-logger/4-20ma-current-loop-measurements.html). Only downside is the base unit only does 240 hz sampling for $149, you have to pay another $195 for the "high speed" software key to unlock it to do 10 khz. ----- Regards, Carl Ijames
Reply by ●March 13, 20132013-03-13
"John Devereux" wrote in message news:871ubj9nq5.fsf@devereux.me.uk... Tim Wescott <tim@seemywebsite.com> writes:> On Wed, 13 Mar 2013 12:05:05 -0500, Vladimir Vassilevsky wrote: > >> On 3/13/2013 11:44 AM, Tim Wescott wrote: >> >>> I have a need to sample one channel of data at between 200 and 2000 >>> samples per second, 12 bits or so, and store it away. >> >> For one time deal: take your favorite micro eval board from the shelf; >> connect it to USB to RS232 dongle; put together simple application; >> record file from terminal program on PC. All preparation should take >> less then half an hour. > > It's for a customer over 1000 miles away whose hand I cannot easily hold. > > And it needs to deal with 4-40mA, for which I have no hardware.Like a resistor? :) -- John Devereux This might do http://www.mccdaq.com/usb-data-acquisition/USB-200-Series.aspx --Phil Martel
Reply by ●March 14, 20132013-03-14
"Joerg" <invalid@invalid.invalid> wrote in message news:aqclc8FogvrU1@mid.individual.net...> Tim Wescott wrote: >> On Wed, 13 Mar 2013 16:26:15 -0700, George Herold wrote: >> >>> Tim, Can I ask how you plan to deal with the long data files? >>> >>> George H. >> >> Scilab will happily slurp up multi-megabyte files and process them. >> If >> it starts having problems I can read the file in manageable-sized >> chunks. >> > > Consider storing in chunks. There is always that chance that the > computer croaks in the middle of the game and then at least you have > some data. The usual, Leroy plugging in the big floor buffer machine > ... > tsk ... KATCHOCK ... light out. > > -- > Regards, Joerg > > http://www.analogconsultants.com/We used to do some long 8+hrs data logging tests. After some grumbling, 'they' agreed to put the whole setup on a big 1500VA UPS. It actually saved a half dozen data runs from being corrupted from power disruptions. Cheers
Reply by ●March 14, 20132013-03-14
On a sunny day (Wed, 13 Mar 2013 18:11:17 -0500) it happened Jamie <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote in <GF60t.148683$wI7.5227@newsfe15.iad>:> With today's PC's, it's common to get 192k sampling rates.You can use a 4046 VCO, recod to a soundcard channel, and then display later with a frequency counter :-) In the sities I recorded slow san TV that tway, FM, on tape.
Reply by ●March 14, 20132013-03-14
On Mar 13, 11:44�am, Tim Wescott <t...@seemywebsite.com> wrote:> This is slightly OT for all the groups I'm posting to, but something many > of you should have done. > > I have a need to sample one channel of data at between 200 and 2000 > samples per second, 12 bits or so, and store it away. > > The signal happens to be on a 4-40mA line already, to make life easy for > getting off-the-shelf hardware. > > I need to store hours of guaranteed-uninterrupted data, or failing that, > store data that's timestamped at the measuring device (not just in the PC > software) so that I can see what's missing and deal with it. �(dropouts > of even a half second or so would be OK, as long as the timestamps are > correct). > > The mental model I'm carrying around is a laptop PC, connected to some > little box via USB, quietly buzzing away in a corner making multi- > megabyte files with the information I want. > > I assume that this is a no-brainer with National Instruments hardware and > software -- am I correct? �If not, is there a solution that you can > recommend? �Do you have a favorite other than NI? >Could you do with only 10-bit resolution? The Dataq DI-194 is $60. Or the DI-155 for $150 has 13 bit resolution. http://www.dataq.com/data-acquisition-starter-kits/data-acquisition-starter-kits.htm I've used their stuff for some 20-odd years and have always been happy with it. Interfaces to LabView if needed, or they include a simple free logger/reader program.
