On Wed, 13 Mar 2013 14:05:10 -0700, langwadt@fonz.dk wrote:> On Mar 13, 9:54 pm, Joerg <inva...@invalid.invalid> wrote: >> langw...@fonz.dk wrote: >> > On Mar 13, 6:19 pm, Tim Wescott <t...@seemywebsite.com> wrote: >> >> 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. >> >> >> But it's a tempting idea. >> >> > you really mean 4-40mA not the usual 4-20mA ? >> >> In America everything is a little bigger :-) > > ;) > > >> > anyway it is just a resistor >> >> > if you can live with 10 bits, something like this won't even need a >> > pc >> >> >https://www.sparkfun.com/products/10216 >> >> These are cool, but not enough memory for Tim's job: >> >> http://www.lascarelectronics.com/temperaturedatalogger.php?datalogger...>> >> > yeh and much too slow, maximum is 1Hz, he wants +200Hz > > -LasseBut other than inadequate speed and inadequate memory, it looks great! -- 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 & Software http://www.wescottdesign.com
PC Data Acquisition
Started by ●March 13, 2013
Reply by ●March 13, 20132013-03-13
Reply by ●March 13, 20132013-03-13
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. Jamie
Reply by ●March 13, 20132013-03-13
On 3/13/2013 3:47 PM, John Larkin wrote:> On Wed, 13 Mar 2013 12:04:34 -0700, Joerg <invalid@invalid.invalid> > wrote: > >> John Larkin wrote: >>> On Wed, 13 Mar 2013 11:10:30 -0700, Rob Gaddi >>> <rgaddi@technologyhighland.invalid> wrote: >>> >>>> On Wed, 13 Mar 2013 10:54:17 -0700 >>>> Joerg <invalid@invalid.invalid> 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? >>>>>> >>>>> I usually use this for such jobs: >>>>> >>>>> http://labjack.com/u3 >>>>> >>>>> Plus a few resistors. It also comes in a version for LAN connection in >>>>> case that's more practical. >>>>> >>>>> It comes with a light version of Azeotech SCADA software which is really >>>>> handy if you don't want to mess with computer programming or Excel-VBA >>>>> too much. If you get stuck both Labjack and Azeotech have rather >>>>> responsive forums where their respective support staff chimes in. And if >>>>> someone screws up a PID you can become the expert and help them out :-) >>>>> >>>>> -- >>>>> Regards, Joerg >>>>> >>>>> http://www.analogconsultants.com/ >>>> Wow. I was actually just wondering about something like this the other day. And the fact that it comes complete with cross-platform drivers and Python bindings makes it pretty seriously nifty. >>> >>> It should just enumerate as an FTDI serial port, so there would be no >>> need for drivers and DLLs. >>> >> >> Not quite. It has a whole slew of settings that are handled by the >> driver, AFAIK. It even has a simple set panel where you could goose a >> DAC, set a port or read an ADC value (they all show up in the window). >> Then there's things like streaming mode and so on. It also needs to know >> whether it has foreign device connected to it and whether they should be >> addressed with RS232, "Her Majesty" or SPI. > > These use the FTDI chip, which is the most common and most reliable > USB-serial interface: > > http://www.ftdichip.com/Support/Documents/DataSheets/DLP/dlp-io20-ds-v10.pdf > > http://www.mouser.com/ds/2/117/DLP-IO14-188487.pdf > > http://www.ftdichip.com/Support/Documents/DataSheets/DLP/dlp-io8-ds-v15.pdf > > > These generally have a control panel app, and maybe a data logger. But > they are also easy to access from a programming language, as a COM > port. > > >LabJack comes with C bindings as well as Python. I'm currently using a U6 Pro to run a prototype spectrometer. 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
Tim Wescott wrote:> On Wed, 13 Mar 2013 14:05:10 -0700, langwadt@fonz.dk wrote: > >> On Mar 13, 9:54 pm, Joerg <inva...@invalid.invalid> wrote: >>> langw...@fonz.dk wrote:[...]>>>> anyway it is just a resistor >>>> if you can live with 10 bits, something like this won't even need a >>>> pc >>>> https://www.sparkfun.com/products/10216 >>> These are cool, but not enough memory for Tim's job: >>> >>> http://www.lascarelectronics.com/temperaturedatalogger.php? > datalogger... >>> >> yeh and much too slow, maximum is 1Hz, he wants +200Hz >> >> -Lasse > > > But other than inadequate speed and inadequate memory, it looks great! >They also make these nice small bench supplies, John Larkin has a few. And every time I called them some with a nice Bri'ish accent answered :-) -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●March 13, 20132013-03-13
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. -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●March 13, 20132013-03-13
On Mar 13, 12:44�pm, 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? > > TIA. > > -- > 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.comTim, Can I ask how you plan to deal with the long data files? George H.
Reply by ●March 13, 20132013-03-13
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. -- 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 & Software http://www.wescottdesign.com
Reply by ●March 13, 20132013-03-13
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 & Software http://www.wescottdesign.com
Reply by ●March 13, 20132013-03-13
On Mar 13, 4:22�pm, Spehro Pefhany <speffS...@interlogDOTyou.knowwhat> wrote:> On Wed, 13 Mar 2013 11:10:30 -0700, Rob Gaddi > > > > > > <rga...@technologyhighland.invalid> wrote: > >On Wed, 13 Mar 2013 10:54:17 -0700 > >Joerg <inva...@invalid.invalid> 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? > > >> I usually use this for such jobs: > > >>http://labjack.com/u3 > > >> Plus a few resistors. It also comes in a version for LAN connection in > >> case that's more practical. > > >> It comes with a light version of Azeotech SCADA software which is really > >> handy if you don't want to mess with computer programming or Excel-VBA > >> too much. If you get stuck both Labjack and Azeotech have rather > >> responsive forums where their respective support staff chimes in. And if > >> someone screws up a PID you can become the expert and help them out :-) > > >> -- > >> Regards, Joerg > > >>http://www.analogconsultants.com/ > > >Wow. �I was actually just wondering about something like this the other day. �And the fact that it comes complete with cross-platform drivers and Python bindings makes it pretty seriously nifty. > > Maybe 1% of the cost of a NI solution.- Hide quoted text - > > - Show quoted text -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.
Reply by ●March 13, 20132013-03-13
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
