PC Data Acquisition

On 3/13/2013 6:54 PM, Joerg wrote:


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
  Click to see the full signature.
Add pictures here
โœ–
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Wed, 13 Mar 2013 11:10:30 -0700, Rob Gaddi

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.
Add pictures here
โœ–
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Spehro Pefhany wrote:

And the fact that it comes complete with cross-platform drivers and Python bindings makes it pretty seriously nifty.

And no membership fees for continued support. My own Labjack is many years old. Got stuck somewhere recently, asked, received a response within the hour, problem fixed.
--
Regards, Joerg

http://www.analogconsultants.com/
  Click to see the full signature.
Add pictures here
โœ–
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

many

for

hat,

he PC

pouts

re

me

e and

n
ly

if

)
r day.  And the fact that it comes complete with cross-platform drivers a nd Python bindings makes it pretty seriously nifty.

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.
Add pictures here
โœ–
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Wed, 13 Mar 2013 16:45:06 -0700 (PDT), the renowned George Herold

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"
snipped-for-privacy@interlog.com Info for manufacturers: http://www.trexon.com
  Click to see the full signature.
Add pictures here
โœ–
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Grumble...

"The Journey is the reward"
www.trexon.com

eff.com
Add pictures here
โœ–
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Wed, 13 Mar 2013 20:13:53 -0400, Spehro Pefhany

Do you mean glitzy substandard?
?-)
Add pictures here
โœ–
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Wed, 13 Mar 2013 16:45:06 -0700 (PDT), George Herold

something many

2000

easy for

failing that,

in the PC

 (dropouts

timestamps are

some

multi-

hardware and

can

in

really

Excel-VBA

And if

:-)

other day.  And the fact that it comes complete with cross-platform drivers and Python bindings makes it pretty seriously nifty.

Well shucks, NI has to do something with all those support dollars.
?-(
Add pictures here
โœ–
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Followups set to sci.electronics.design .

You already own A/D hardware and software that can sample two 16-bit channels at up to 44 kHz with an amplitude of roughly one volt. These days it's integrated but the board used to say "SoundBlaster" on it. Just bypass the DC blocking caps on the input.

With some soundcards, it's possible to record from the left and right channels separately. You could feed the same signal to both channels and then stagger the file gaps so that one of the channels is always recording. I'd do something like "new file every 5 to 10 minutes"; that way you can go with the file timestamp and the sample count to establish an exact time of the event of interest. Use something like Audacity to look at the files, or use SoX (Sound eXchange) to convert the .WAV files you will probably get into raw binary files, which you can then concatenate back together, or scan through in your favorite programming language.
If you can, it might be worthwhile to run the application on the target PC for several hours and see how bad the PC's internal clock drifts. Some are good and some can be out several seconds over the course of a day.

If you use Windows, try to have the machine not be on a network, and shut off all the Windows updates, anti-virus updates, etc. These can randomly munch large amounts of your disk and CPU and maybe affect the data acquisition.

They probably sell a card or USB dongle that can do it, in conjunction with Labview. Be sure you are sitting down when you ask about the price, and plan on having a fairly stout PC to run Labview on. Measurement Computing probably sells something equivalent for slightly less money. If you don't already own Labview, and you have the ability to write your own code, you can probably reduce the cost somewhat; despite NI's advertising, a first-time Labview user is *not* going to get something to work in 5 minutes.
Matt Roberds
Add pictures here
โœ–
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Tim Wescott wrote:

Got a parallel port? Should be LPC... Intel sez it's up to 2Megabytes/s. Not sure if true..
Snippets: https://github.com/klammerj/DOSpar
Add pictures here
โœ–
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Does it harm if 50/60 Hz mains hum is inserted into the ADC input ? Missing samples could be detected by discontinuous in the 50/60 Hz tone.

Are you sure about 4-40 mA ? Standard industrial devices are 4-20 mA ?

Use the current loop to modulate some voltage/frequency converter and use standard sound card to detect the signal. An audio transformer will take care of any ground loop (hum) problems.
Add pictures here
โœ–
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Wed, 13 Mar 2013 22:29:41 +0200, upsidedown wrote:

Oops...
--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
  Click to see the full signature.
Add pictures here
โœ–
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Tim Wescott wrote:

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
Add pictures here
โœ–
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Wed, 13 Mar 2013 18:11:17 -0500, Jamie wrote:

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.
  Click to see the full signature.
Add pictures here
โœ–
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Tim Wescott wrote:

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
Add pictures here
โœ–
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
[quote] "Jamie" wrote in message
Tim Wescott wrote:

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
Add pictures here
โœ–
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On a sunny day (Wed, 13 Mar 2013 18:11:17 -0500) it happened Jamie
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.
Add pictures here
โœ–
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Jan Panteltje wrote:

Yeah well, I wrote a slow scan TV program for windows :)
Jamie
Add pictures here
โœ–
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

ttdesign.com
Tim, Can I ask how you plan to deal with the long data files?
George H.
Add pictures here
โœ–
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Wed, 13 Mar 2013 16:26:15 -0700, George Herold wrote:

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.
  Click to see the full signature.
Add pictures here
โœ–
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.