Current measurements from a computer

[MIke Brown]

Hello,

Does anyone know of a good way to get DC current measurements from a
standard computer (via rs232,etc)?

Do most of the rs232 capable multimeters out there support reading
current measurements live (or do they just log?)

I can't seem to find a good device out there that is rs232 or rs422
capable to read current/voltage. I really don't need anything battery
powered, with a display or anything. I'm even considering making one
for fun, but my electronics ability is still basic/moderate.

-Mike

 

[Alan B]

Hello,

Does anyone know of a good way to get DC current measurements from a
standard computer (via rs232,etc)?

What do you mean? Are you saying you want to log a series of measurements
to your computer via an RS-232 interface? If so, you should be able to
easily find data logging devices that can do this for you. For instance:

http://www4.tpgi.com.au/users/p8king/qm1538.htm

Do most of the rs232 capable multimeters out there support reading
current measurements live (or do they just log?)

Umm, ok, so you want to set up your computer device to do virtual real-time
readouts as the DMM is logging? Reading the promo for the above device
seems to show that it comes with the software that does exactly that. The
vendor could be contacted for specifics.

I can't seem to find a good device out there that is rs232 or rs422
capable to read current/voltage. I really don't need anything battery
powered, with a display or anything. I'm even considering making one
for fun, but my electronics ability is still basic/moderate.

Yes, well, I don't want to be rude here (heaven knows I'm *very* good at
it), but I did a web search on <"data logging" rs-232 DMM>, and the above
link was the first hit.

 

[Jim Land]

Hello,

Does anyone know of a good way to get DC current measurements from a
standard computer (via rs232,etc)?

Do most of the rs232 capable multimeters out there support reading
current measurements live (or do they just log?)

I can't seem to find a good device out there that is rs232 or rs422
capable to read current/voltage. I really don't need anything battery
powered, with a display or anything. I'm even considering making one
for fun, but my electronics ability is still basic/moderate.

The only reason to bring a PC into the picture is if you want to log the
data.

If all you want is live readings of voltage or current, buy a digital
multimeter. You'll get accurate readings, have a useful (indispensable)
piece of test gear, and save yourself a lot of trouble trying to make
your own.

Example:
http://www.tequipment.net/ElencoM-1750.html

 

[Alan B]

The only reason to bring a PC into the picture is if you want to log the
data.

Well, that's not the only reason, but the other reasons I'm thinking of
might be beyond the scope of the newsgroup.

 

[Chris]

Hello,

Does anyone know of a good way to get DC current measurements from a
standard computer (via rs232,etc)?

Do most of the rs232 capable multimeters out there support reading
current measurements live (or do they just log?)

I can't seem to find a good device out there that is rs232 or rs422
capable to read current/voltage. I really don't need anything battery
powered, with a display or anything. I'm even considering making one
for fun, but my electronics ability is still basic/moderate.

-Mike

Hi, Mike. Just about all of the RS-232 capable handheld DMMs have DC
and AC current ranges. Most of them can be set to spew the display
numbers at fixed intervals (usually once a second or so).

As an example, the one sold at Radio Shack (Model: 22-812, $69.99 USD
ea.) does both. By default, it just spits out the reading every second
in real time once you start it with pressing the SELECT and RANGE
buttons together. The meter also comes with software for data logging,
but if you are capable of programming an RS-232 port, you can go ahead
and use the data as it becomes available.

Far easier to just buy it than going through the rigors of reinventing
the wheel by making one.

Good luck
Chris

 

[Bob Masta]

Hello,

Does anyone know of a good way to get DC current measurements from a
standard computer (via rs232,etc)?

Do most of the rs232 capable multimeters out there support reading
current measurements live (or do they just log?)

I can't seem to find a good device out there that is rs232 or rs422
capable to read current/voltage. I really don't need anything battery
powered, with a display or anything. I'm even considering making one
for fun, but my electronics ability is still basic/moderate.

-Mike

Not exactly what you asked for, but Dataq has a starter kit
with a 4-channel 10-bit ADC that connects to the serial
port and comes with data logging software for only US$24.95.

http://www.dataq.com/194.htm

The ADC ranges are +/-10 VDC, so you'd need to add your
own current-to-voltage converter ahead of this.

(No affiliation, just recognize a bargain. They used to give
these things away for free... and it looks like maybe they
still do for high school science fairs.)

Best regards,


Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Home of DaqGen, the FREEWARE signal generator

 

[[email protected]]

The only reason to bring a PC into the picture is if you want to log the
data.

If all you want is live readings of voltage or current, buy a digital
multimeter. You'll get accurate readings, have a useful (indispensable)
piece of test gear, and save yourself a lot of trouble trying to make
your own.

Example:
http://www.tequipment.net/ElencoM-1750.html

To actually measure though, should be scrape away some of the rs232
cable and stick his probes there. ?
And since - I think - current is measured in series, would he have to
cut the cable /cut an extension cable. ?

 

[Jim Land]

[email protected] wrote in 75g2000cwc.googlegroups.com:

To actually measure though, should be scrape away some of the rs232
cable and stick his probes there. ?
And since - I think - current is measured in series, would he have to
cut the cable /cut an extension cable. ?

The OP didn't say he wanted to measure voltage or current at his RS232
outlet. He said he wanted to connect a voltmeter (measuring a voltage
somewhere else) to his PC through the RS232 connector.

The point is, why pass measurement data from a voltmeter to a PC? What
good does that do? Maybe if you want to log measurements every five
minutes for a week.