Re: OT: AC power to run a DMM

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Re: OT: AC power to run a DMM

Jeff Shanab
> Lee said
...
> I've used several brands of these meters with "PC compatible" RS-232
> ports (Radio Shack, DataPro, and Metex). They all had optically
> isolated serial ports, with no connection between the serial data and
> any meter input terminals. However, there could be some that do.
...

I just wanted to mention that I bought some radio shack meters with
rs232 output (#22-812) without reading the instructions. They send a
stream of bytes where the bits represent which LCD segments are on or
off. The translation is "fun". RTFM

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Re: OT: AC power to run a DMM

Lee Hart
Jeff Shanab wrote:

>> Lee said
> ...
>> I've used several brands of these meters with "PC compatible" RS-232
>> ports (Radio Shack, DataPro, and Metex). They all had optically
>> isolated serial ports, with no connection between the serial data and
>> any meter input terminals. However, there could be some that do.
> ...
>
> I just wanted to mention that I bought some radio shack meters with
> rs232 output (#22-812) without reading the instructions. They send a
> stream of bytes where the bits represent which LCD segments are on or
> off. The translation is "fun". RTFM

I had that problem, too. The older meters (Radio Shack 22-168 and
22-805) output plain ASCII -- "-12.34 VDC<CR>" for example. The newer
ones just send raw segment data in an undocumented format, and depend on
a Windows PC program to figure out what it means.

--
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in    --    Leonard Cohen
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net

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Re: OT: AC power to run a DMM

Chuck Hursch-2
Lee Hart wrote:
> Jeff Shanab wrote:
> >> Lee said
> > ...
> >> I've used several brands of these meters with "PC
compatible" RS-232
> >> ports (Radio Shack, DataPro, and Metex). They all had
optically
> >> isolated serial ports, with no connection between the serial
data and
> >> any meter input terminals. However, there could be some that
do.
> > ...
> >
> > I just wanted to mention that I bought some radio shack
meters with
> > rs232 output (#22-812) without reading the instructions. They
send a
> > stream of bytes where the bits represent which LCD segments
are on or
> > off. The translation is "fun". RTFM
>
> I had that problem, too. The older meters (Radio Shack 22-168
and
> 22-805) output plain ASCII -- "-12.34 VDC<CR>" for example. The
newer
> ones just send raw segment data in an undocumented format, and
depend on
> a Windows PC program to figure out what it means.

At this point, I'm leaning towards the 22-812.  Looks like a nice
meter.  I'll probably use zmeter from sourceforge.net to
interpret the RS-232 output (I'm planning on doing this on a
Linux variant - Ubuntu on the laptop I acquired a couple of
months ago).  Appears that the RS-232 output is isolated from the
voltage leads with an infrared connection between them (so an
opto-isolator).  (I had ideas about using a RS-232/bluetooth
adapter to obtain my isolation, but those appear expensive, and
I'll rely on the 22-812 actually being isolated.)

Downside of buying another meter, is well, another meter.  Got
too much stuff around in this here apt!  Too many voltmeters.
But something I can take data with and put it on a computer will
be nice...

I assume the 22-812 does not have an auto shutoff feature, as Lee
mentioned some models do.  I just downloaded the manual for the
22-812, so I'll dig into that.

EVDL Administrator (David Roden) wrote:
> The quick and dirty method : get a small, inexpensive 12:120v
inverter --
> you need only a few watts of capacity -- and connect the input
to your
> accessory battery.  Plug a 9v wall wart into the inverter.
Connect wall
> wart to DMM.  Done.

I'll see how long the first 9V battery lasts.  If the battery
dies in a hurry, I'll start looking at doing this kind of stuff.
I have a 140W inverter (w/ no fan overhead).  Would have to make
a hookup for the Anderson connector in the back of the car (where
I'll be taking data in the hatchback area).  I don't know what
the overhead of the inverter is (I suspect it will be mostly
inverter overhead and not so much powering the 22-812).  My DC-DC
is tied to the key-switch in the VoltsRabbit kit.  Every other
night I leave the key-switch turned on to give the aux. battery a
chance to catch up when I get back home while I'm eating before I
plug the car in for the night.  (Before I started doing that, my
aux. batteries didn't last very long.)  Being in an apt. complex
means that I don't leave that key in there for long unattended.
So whether an added inverter load is a good idea, I don't know...

Alternatively, Lee Hart wrote:
> One more option: Keep in mind that these multimeters rarely
draw more
> than 5 ma from their 9v battery. That's so low that a pack of 6
D cells
> will last months even if you left it on all the time.

Were you thinking of stuffing the 6 D cells into a plastic tube
and somehow getting good connections on the end?  I have a
plastic battery tray for attaching two small batteries (AA) to a
solar panel.  I don't know if such a thing is made for 6 big D
cells (if you've seen one pls point me to it).

Will have to think of a good way to avoid damaging the fragile 9V
battery clip in the voltmeter.

Thanks all for your suggestions!

Chuck

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Re: OT: AC power to run a DMM

Lee Hart
Chuck Hursch wrote:
> At this point, I'm leaning towards the 22-812.  Looks like a nice
> meter.  I'll probably use zmeter from sourceforge.net to
> interpret the RS-232 output (I'm planning on doing this on a
> Linux variant - Ubuntu on the laptop I acquired a couple of
> months ago).

That should work, though it ain't exactly elegant to use a linux
computer for what should be a simple task.

> Appears that the RS-232 output is isolated from the
> voltage leads with an infrared connection between them (so an
> opto-isolator).

Correct; there's an optocoupler in it.

Lee Hart wrote:
>> One more option: a pack of 6 D cells will last months even if you
>> left it on all the time.

> Were you thinking of stuffing the 6 D cells into a plastic tube
> and somehow getting good connections on the end?

I'd get a proper 6-cell battery holder for D-cells, and put it in a
plastic case of some kind (the D cells will be "hot" to your propulsion
pack voltage). A decent quality battery holder will be fine,
reliability-wise.

> I have a plastic battery tray for attaching two small batteries (AA)
> to a solar panel. I don't know if such a thing is made for 6 big D
> cells (if you've seen one pls point me to it).

I haven't looked, but they probably do. Even if not, there is no magic
to connecting the D cells to a solar panel. If you use nicad D cells,
they won't need any charge controller as they can absorb at least 10% of
the amphour rating indefinitely (like 500ma for 5ah cells). You aren't
likely to use a solar panel anywhere near that big.

> Will have to think of a good way to avoid damaging the fragile 9V
> battery clip in the voltmeter.

Here again, they make good ones, and cheap ones (but few good cheap ones).
--
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in    --    Leonard Cohen
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net

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Re: OT: AC power to run a DMM

evan foss
On Thu, Feb 5, 2009 at 8:17 PM, Lee Hart <[hidden email]> wrote:

> Chuck Hursch wrote:
>> At this point, I'm leaning towards the 22-812.  Looks like a nice
>> meter.  I'll probably use zmeter from sourceforge.net to
>> interpret the RS-232 output (I'm planning on doing this on a
>> Linux variant - Ubuntu on the laptop I acquired a couple of
>> months ago).
>
> That should work, though it ain't exactly elegant to use a linux
> computer for what should be a simple task.
>
>> Appears that the RS-232 output is isolated from the
>> voltage leads with an infrared connection between them (so an
>> opto-isolator).
>
> Correct; there's an optocoupler in it.
>
> Lee Hart wrote:
>>> One more option: a pack of 6 D cells will last months even if you
>>> left it on all the time.
>
>> Were you thinking of stuffing the 6 D cells into a plastic tube
>> and somehow getting good connections on the end?
>
> I'd get a proper 6-cell battery holder for D-cells, and put it in a
> plastic case of some kind (the D cells will be "hot" to your propulsion
> pack voltage). A decent quality battery holder will be fine,
> reliability-wise.

I like this idea but if you are not using a solar panel packaged for
battery charging you should add a diode. The diode will protect the
solar cells from power going back from the battery into them.

>
>> I have a plastic battery tray for attaching two small batteries (AA)
>> to a solar panel. I don't know if such a thing is made for 6 big D
>> cells (if you've seen one pls point me to it).
>
> I haven't looked, but they probably do. Even if not, there is no magic
> to connecting the D cells to a solar panel. If you use nicad D cells,
> they won't need any charge controller as they can absorb at least 10% of
> the amphour rating indefinitely (like 500ma for 5ah cells). You aren't
> likely to use a solar panel anywhere near that big.
>
>> Will have to think of a good way to avoid damaging the fragile 9V
>> battery clip in the voltmeter.
>
> Here again, they make good ones, and cheap ones (but few good cheap ones).
> --
> Ring the bells that still can ring
> Forget the perfect offering
> There is a crack in everything
> That's how the light gets in    --    Leonard Cohen
> --
> Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
>
> _______________________________________________
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> Usage guidelines: http://evdl.org/help/index.html#conv
> Archives: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>
>



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Re: OT: AC power to run a DMM

Zeke Yewdall
In reply to this post by Chuck Hursch-2
On Thu, Feb 5, 2009 at 4:15 PM, Chuck Hursch <[hidden email]> wrote:

Most of those small inverters run around a quarter amp (3 or 4 watts) with
no load.

And, also, they do not tend to be isolated, between the 12 volt side and the
120 volt side -- just so you know.  If you ground the AC hot out it'll shut
itself off, but if you ground the AC-nuetral out it will just blow out the
main transistor bank.

Z

>
>
> I have a 140W inverter (w/ no fan overhead).  Would have to make
> a hookup for the Anderson connector in the back of the car (where
> I'll be taking data in the hatchback area).  I don't know what
> the overhead of the inverter is (I suspect it will be mostly
> inverter overhead and not so much powering the 22-812).  My DC-DC
> is tied to the key-switch in the VoltsRabbit kit.  Every other
> night I leave the key-switch turned on to give the aux. battery a
> chance to catch up when I get back home while I'm eating before I
> plug the car in for the night.  (Before I started doing that, my
> aux. batteries didn't last very long.)  Being in an apt. complex
> means that I don't leave that key in there for long unattended.
> So whether an added inverter load is a good idea, I don't know...
>
>
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Re: OT: AC power to run a DMM

Jeff Shanab
In reply to this post by Jeff Shanab
> Chuck Hursch wrote:
>> At this point, I'm leaning towards the 22-812.  Looks like a nice
>> meter.  I'll probably use zmeter from sourceforge.net to
>> interpret the RS-232 output (I'm planning on doing this on a
>> Linux variant - Ubuntu on the laptop I acquired a couple of
>> months ago).
>
> That should work, though it ain't exactly elegant to use a linux
> computer for what should be a simple task.
<snip>

Where I work they have linux based computers on boards that are less
than 2" square and use power over ethernet for their power. I can ssh
into them and it contains a full file system and runs a video streaming
server, a web server for configuration, and other upnp apps. I was
really impressed with how scalable linux can be. Linux also makes
develop on desktop for a different target pretty easy. It got me
interested in linux mini computers like the gumstix and uClinux and the
little ethernet port with a linux computer in it.

http://www.gumstix.com/               Cool periperials, reasonable
price, Very Active (Note robostix)

http://www.uclinux.org/ucsimm/   slow web, old project, not so active

http://www.picotux.com/               OMG!

Perhaps one of these would work well.
I had written a C program to read from the meter, but I can't find it :-(

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Re: OT: AC power to run a DMM

evan foss
On Fri, Feb 6, 2009 at 9:53 AM, Jeff Shanab <[hidden email]> wrote:

>> Chuck Hursch wrote:
>>> At this point, I'm leaning towards the 22-812.  Looks like a nice
>>> meter.  I'll probably use zmeter from sourceforge.net to
>>> interpret the RS-232 output (I'm planning on doing this on a
>>> Linux variant - Ubuntu on the laptop I acquired a couple of
>>> months ago).
>>
>> That should work, though it ain't exactly elegant to use a linux
>> computer for what should be a simple task.
> <snip>
>
> Where I work they have linux based computers on boards that are less
> than 2" square and use power over ethernet for their power. I can ssh
> into them and it contains a full file system and runs a video streaming
> server, a web server for configuration, and other upnp apps. I was
> really impressed with how scalable linux can be. Linux also makes
> develop on desktop for a different target pretty easy. It got me
> interested in linux mini computers like the gumstix and uClinux and the
> little ethernet port with a linux computer in it.

It isn't about footprint it is about using a sledge hammer to pound in
a thumbtack. I understand the motivation to use it though. It is easy
and fast, the buzzword now is rapid prototyping but it is more than
just a little overkill. I prefer typically in cases like this to start
off doing it the way you are if the task is a large one and after it
works go back and redo with something more appropriate. It is just a
question of taste and budget though.
68HC11 with gluechips $40
Embedded linux kit >$100

That said what you are doing is still cool.

>
> http://www.gumstix.com/               Cool periperials, reasonable
> price, Very Active (Note robostix)
>
> http://www.uclinux.org/ucsimm/   slow web, old project, not so active
>
> http://www.picotux.com/               OMG!
>
> Perhaps one of these would work well.
> I had written a C program to read from the meter, but I can't find it :-(
>
> _______________________________________________
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>



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Re: OT: AC power to run a DMM

Chuck Hursch-2
evan foss wrote:
> On Fri, Feb 6, 2009 at 9:53 AM, Jeff Shanab
<[hidden email]> wrote:
> >> Chuck Hursch wrote:
> >>> At this point, I'm leaning towards the 22-812.  Looks like
a nice
> >>> meter.  I'll probably use zmeter from sourceforge.net to
> >>> interpret the RS-232 output (I'm planning on doing this on
a
> >>> Linux variant - Ubuntu on the laptop I acquired a couple of
> >>> months ago).
> >>
> >> That should work, though it ain't exactly elegant to use a
linux
> >> computer for what should be a simple task.
> > <snip>

All I've got right now for this little project is a laptop given
from the estate of an EV friend who can no longer use it, because
of health reasons.  Had only WinXP before, but I had it made into
a multi-boot machine with Ubuntu Linux.  I'd much rather work in
Linux and some C/C++/Java variant than Windoze.  I plan on
getting some kind of data stream working with the Linux platform,
then at some point I'd be working into the small micros as
mentioned below.

Unfortunately, yesterday I got tuned into the fact that this
laptop has no RS-232 port, only a USB port, so that may add a
level of complication.
> >
> > Where I work they have linux based computers on boards that
are less
> > than 2" square and use power over ethernet for their power. I
can ssh
> > into them and it contains a full file system and runs a video
streaming
> > server, a web server for configuration, and other upnp apps.
I was
> > really impressed with how scalable linux can be. Linux also
makes
> > develop on desktop for a different target pretty easy. It got
me
> > interested in linux mini computers like the gumstix and
uClinux and the
> > little ethernet port with a linux computer in it.
>
> It isn't about footprint it is about using a sledge hammer to
pound in
> a thumbtack. I understand the motivation to use it though. It
is easy
> and fast, the buzzword now is rapid prototyping but it is more
than
> just a little overkill. I prefer typically in cases like this
to start
> off doing it the way you are if the task is a large one and
after it
> works go back and redo with something more appropriate. It is
just a
> question of taste and budget though.
> 68HC11 with gluechips $40
> Embedded linux kit >$100
>
> That said what you are doing is still cool.
>
> >
> > http://www.gumstix.com/               Cool periperials,
reasonable
> > price, Very Active (Note robostix)
> >
> > http://www.uclinux.org/ucsimm/   slow web, old project, not
so active
> >
> > http://www.picotux.com/               OMG!
> >
> > Perhaps one of these would work well.
> > I had written a C program to read from the meter, but I can't
find it :-(
> >
> > _______________________________________________
> > General EVDL support: http://evdl.org/help/
> > Usage guidelines: http://evdl.org/help/index.html#conv
> > Archives: http://evdl.org/archive/
> > Subscription options:
http://lists.sjsu.edu/mailman/listinfo/ev

> >
> >
>
>
>
> --
> http://www.coe.neu.edu/~efoss/
> http://evanfoss.googlepages.com/
>
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Re: OT: AC power to run a DMM

evan foss
I wasn't suggesting windows. There are smaller programmable devices
out there for this kind of task than desktop or laptop computers or
smaller versions there of. I was talking about an embedded processor.

On Fri, Feb 6, 2009 at 6:39 PM, Chuck Hursch <[hidden email]> wrote:

> evan foss wrote:
>> On Fri, Feb 6, 2009 at 9:53 AM, Jeff Shanab
> <[hidden email]> wrote:
>> >> Chuck Hursch wrote:
>> >>> At this point, I'm leaning towards the 22-812.  Looks like
> a nice
>> >>> meter.  I'll probably use zmeter from sourceforge.net to
>> >>> interpret the RS-232 output (I'm planning on doing this on
> a
>> >>> Linux variant - Ubuntu on the laptop I acquired a couple of
>> >>> months ago).
>> >>
>> >> That should work, though it ain't exactly elegant to use a
> linux
>> >> computer for what should be a simple task.
>> > <snip>
>
> All I've got right now for this little project is a laptop given
> from the estate of an EV friend who can no longer use it, because
> of health reasons.  Had only WinXP before, but I had it made into
> a multi-boot machine with Ubuntu Linux.  I'd much rather work in
> Linux and some C/C++/Java variant than Windoze.  I plan on
> getting some kind of data stream working with the Linux platform,
> then at some point I'd be working into the small micros as
> mentioned below.
>
> Unfortunately, yesterday I got tuned into the fact that this
> laptop has no RS-232 port, only a USB port, so that may add a
> level of complication.
>> >
>> > Where I work they have linux based computers on boards that
> are less
>> > than 2" square and use power over ethernet for their power. I
> can ssh
>> > into them and it contains a full file system and runs a video
> streaming
>> > server, a web server for configuration, and other upnp apps.
> I was
>> > really impressed with how scalable linux can be. Linux also
> makes
>> > develop on desktop for a different target pretty easy. It got
> me
>> > interested in linux mini computers like the gumstix and
> uClinux and the
>> > little ethernet port with a linux computer in it.
>>
>> It isn't about footprint it is about using a sledge hammer to
> pound in
>> a thumbtack. I understand the motivation to use it though. It
> is easy
>> and fast, the buzzword now is rapid prototyping but it is more
> than
>> just a little overkill. I prefer typically in cases like this
> to start
>> off doing it the way you are if the task is a large one and
> after it
>> works go back and redo with something more appropriate. It is
> just a
>> question of taste and budget though.
>> 68HC11 with gluechips $40
>> Embedded linux kit >$100
>>
>> That said what you are doing is still cool.
>>
>> >
>> > http://www.gumstix.com/               Cool periperials,
> reasonable
>> > price, Very Active (Note robostix)
>> >
>> > http://www.uclinux.org/ucsimm/   slow web, old project, not
> so active
>> >
>> > http://www.picotux.com/               OMG!
>> >
>> > Perhaps one of these would work well.
>> > I had written a C program to read from the meter, but I can't
> find it :-(
>> >
>> > _______________________________________________
>> > General EVDL support: http://evdl.org/help/
>> > Usage guidelines: http://evdl.org/help/index.html#conv
>> > Archives: http://evdl.org/archive/
>> > Subscription options:
> http://lists.sjsu.edu/mailman/listinfo/ev
>> >
>> >
>>
>>
>>
>> --
>> http://www.coe.neu.edu/~efoss/
>> http://evanfoss.googlepages.com/
>>
>> _______________________________________________
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>
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Re: OT: AC power to run a DMM

evan foss
In reply to this post by Chuck Hursch-2
Oops should have read more carefully. Sorry about that. I hope your
friend gets better.

On Fri, Feb 6, 2009 at 6:39 PM, Chuck Hursch <[hidden email]> wrote:

> evan foss wrote:
>> On Fri, Feb 6, 2009 at 9:53 AM, Jeff Shanab
> <[hidden email]> wrote:
>> >> Chuck Hursch wrote:
>> >>> At this point, I'm leaning towards the 22-812.  Looks like
> a nice
>> >>> meter.  I'll probably use zmeter from sourceforge.net to
>> >>> interpret the RS-232 output (I'm planning on doing this on
> a
>> >>> Linux variant - Ubuntu on the laptop I acquired a couple of
>> >>> months ago).
>> >>
>> >> That should work, though it ain't exactly elegant to use a
> linux
>> >> computer for what should be a simple task.
>> > <snip>
>
> All I've got right now for this little project is a laptop given
> from the estate of an EV friend who can no longer use it, because
> of health reasons.  Had only WinXP before, but I had it made into
> a multi-boot machine with Ubuntu Linux.  I'd much rather work in
> Linux and some C/C++/Java variant than Windoze.  I plan on
> getting some kind of data stream working with the Linux platform,
> then at some point I'd be working into the small micros as
> mentioned below.
>
> Unfortunately, yesterday I got tuned into the fact that this
> laptop has no RS-232 port, only a USB port, so that may add a
> level of complication.
>> >
>> > Where I work they have linux based computers on boards that
> are less
>> > than 2" square and use power over ethernet for their power. I
> can ssh
>> > into them and it contains a full file system and runs a video
> streaming
>> > server, a web server for configuration, and other upnp apps.
> I was
>> > really impressed with how scalable linux can be. Linux also
> makes
>> > develop on desktop for a different target pretty easy. It got
> me
>> > interested in linux mini computers like the gumstix and
> uClinux and the
>> > little ethernet port with a linux computer in it.
>>
>> It isn't about footprint it is about using a sledge hammer to
> pound in
>> a thumbtack. I understand the motivation to use it though. It
> is easy
>> and fast, the buzzword now is rapid prototyping but it is more
> than
>> just a little overkill. I prefer typically in cases like this
> to start
>> off doing it the way you are if the task is a large one and
> after it
>> works go back and redo with something more appropriate. It is
> just a
>> question of taste and budget though.
>> 68HC11 with gluechips $40
>> Embedded linux kit >$100
>>
>> That said what you are doing is still cool.
>>
>> >
>> > http://www.gumstix.com/               Cool periperials,
> reasonable
>> > price, Very Active (Note robostix)
>> >
>> > http://www.uclinux.org/ucsimm/   slow web, old project, not
> so active
>> >
>> > http://www.picotux.com/               OMG!
>> >
>> > Perhaps one of these would work well.
>> > I had written a C program to read from the meter, but I can't
> find it :-(
>> >
>> > _______________________________________________
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>> >
>>
>>
>>
>> --
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>> http://evanfoss.googlepages.com/
>>
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Re: OT: AC power to run a DMM

Jeff Shanab
In reply to this post by Jeff Shanab
>
> On Fri, Feb 6, 2009 at 9:53 AM, Jeff Shanab <[hidden email]> wrote:
>  
>>> >> Chuck Hursch wrote:
>>>      
>>>> >>> At this point, I'm leaning towards the 22-812.  Looks like a nice
>>>> >>> meter.  I'll probably use zmeter from sourceforge.net to
>>>> >>> interpret the RS-232 output (I'm planning on doing this on a
>>>> >>> Linux variant - Ubuntu on the laptop I acquired a couple of
>>>> >>> months ago).
>>>>        
>>> >>
>>> >> That should work, though it ain't exactly elegant to use a linux
>>> >> computer for what should be a simple task.
>>>      
>> > <snip>
>> >
>> > Where I work they have linux based computers on boards that are less
>> > than 2" square and use power over ethernet for their power. I can ssh
>> > into them and it contains a full file system and runs a video streaming
>> > server, a web server for configuration, and other upnp apps. I was
>> > really impressed with how scalable linux can be. Linux also makes
>> > develop on desktop for a different target pretty easy. It got me
>> > interested in linux mini computers like the gumstix and uClinux and the
>> > little ethernet port with a linux computer in it.
>>    
>
> It isn't about footprint it is about using a sledge hammer to pound in
> a thumbtack. I understand the motivation to use it though. It is easy
> and fast, the buzzword now is rapid prototyping but it is more than
> just a little overkill. I prefer typically in cases like this to start
> off doing it the way you are if the task is a large one and after it
> works go back and redo with something more appropriate. It is just a
> question of taste and budget though.
> 68HC11 with gluechips $40
> Embedded linux kit >$100
>
> That said what you are doing is still cool.
>
>  

Trust me. The cost of our embedded linux boards are well under $50 :-),  
Heck I have seen those picotux in magazines at about $50. The higher
cost boards have more features of course.
The computing power of micro controllers has gone up while the power
requirements for a linux embedded has gone down and the newer kernels
are more scalable; indeed you can get linux for the atmel 32bit
"microcontrollers". The line between microcontroller and an embedded
linux microcomputer is really blurred. I think when you factor in
develping the Software, the line crosses earlier.

So what happens is you get to choose between writing everything yourself
and the provided infrastructure and drivers the Linux has.
As soon as you want to save to a usb drive or flash or have a display
and not lose information during selection, it starts to make even more
sense.
But I have seen a circuit to let a PIC use an ide harddrive .  What ever
you put your mind to.

For the record the one camera has a max power usage of 11W while serving
up to 4 video streams, the web UI, and alarm array and a relay array,
ssh etc,etc.
I took a look at the chip and it is about 3/8" square. that is the cpu
and the flash. sweet.

I don't know why that surprises me, I loaded linux on my phone, and it
is similar hardware.



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Re: OT: AC power to run a DMM

Cor van de Water
In reply to this post by Chuck Hursch-2
Chuck Hursch wrote:
>Unfortunately, yesterday I got tuned into the fact that this
>laptop has no RS-232 port, only a USB port, so that may add a
>level of complication.

Almost no newer laptop has an RS-232 port these days.
No problem, just buy an RS-232 dongle, this is a cable
that has a USB-RS232 converter in its plug and a few feet
of USB cable to plug into your laptop.
They are plentiful and cheap on Ebay though make sure you
save the install disk and try to see beforehand if it will
work on Linux or check if a driver has been made available
for the particular dongle.
The cheapest cable I found had a HL-340 and I had to reinstall
the driver when my Windows box crashed. Took me almost an hour
to find a driver again without requiring a subscription to a
driver database site.
Note: don't be afraid to download the original driver from
the Chinese manufacturer's website.

Success,

Cor van de Water
Director HW & Systems Architecture Group
Proxim Wireless Corporation http://www.proxim.com
Email: [hidden email]    Private: http://www.cvandewater.com
Skype: cor_van_de_water     IM: [hidden email]
Tel: +1 408 383 7626        VoIP: +31 20 3987567 FWD# 25925
Tel: +91 (040)23117400 x203 XoIP: +31877841130

Please consider the environment before printing this e-mail.

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Re: OT: AC power to run a DMM

Lee Hart
In reply to this post by Jeff Shanab
>> It isn't about footprint it is about using a sledge hammer to pound
>> in a thumbtack.

Jeff Shanab wrote:
> Trust me. The cost of our embedded linux boards are well under $50
> :-), The computing power of micro controllers has gone up while the
> power requirements for a linux embedded has gone down... one camera
> has a max power usage of 11W while serving up to 4 video streams, the
> web UI, and alarm array and a relay array, ssh etc.

OK, so it's a small sledgehammer. But it's still a hammer. Shouldn't you
push a thumbtack in with your thumb?

My Radio Shack 22-168A digital multimeter with RS-232 interface used 9v
at 7.5ma = 0.0675 watts to produce clear ASCII data. Is it progress to
leave the intelligence out of the meter to save a dollar, but then use a
a computer that requires 100's of times more power to interpret what it
says?

The meters in my old EVs were analog -- they needed *no* separate power
supply (they ran off the signal they were measuring, and drew only
microamps). The $10 digital LCD meters with the ICL7106 chip use less
than 1 ma -- we've had them for over 20 years now. Likewise, we've had
solar calculators that run on room ambient light, and watches that run
for a year on a tiny battery.

Designers *know* how to build low power electronics. They just don't
bother! There is still this attitude that power is free and unlimited --
use all you want! Stupid engineering is cheap and easy, and that's all
we want. But cheap and easy does not lead to good long-term solutions.

--
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in    --    Leonard Cohen
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net

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Re: OT: AC power to run a DMM

Cor van de Water
Which chip is used in that DMM?
Can't it be switched between outputing
raw display segments and ASCII or comparable data?

BTW, it is not surprising that the meter uses
much less power than the Linux stamp, because
the meter has one dedicated application so it
can be optimally written for that and needs
a minimal amount of processing power, clock
frequencies may be in KiloHertz instead of in
MegaHertz.
These poststamp sized generic controllers
running Linux are a marvel of integration and
flexibility.
You can load an application almost as easy on
your home computer as on one of these, very
little porting or customization needed.

So - a sledgehammer? Yes, maybe. But very
customizeable so it can pound in heavy nails
but also push a thumbtack into your sheetrock.

Try to load the DMM application onto your PC,
I mean - even if you would have the code, you
would not be able to port it to your operating
system easily. Try modifying your DMM to display
the balance between your batteries, you will
find it was made for only very specific tasks.
Running applications on Linux, whether home PC
or poststamp controller, allows you to use it
for a variety of tasks without rewriting the
code every time.
So maybe it is overkill and consumes more power
than strictly needed but I think a few Watts
for a set of important tasks in an EV is a
good use of such a controller.
Besides, developing dedicated hardware to
optimize this solution to the level of a DMM
would mean that it will never finish so it
will not be used. The Linux stamp is good
enough and as is often quoted, Perfect is
the enemy of the Good.

Regards,

Cor van de Water
Director HW & Systems Architecture Group
Proxim Wireless Corporation http://www.proxim.com
Email: [hidden email]    Private: http://www.cvandewater.com
Skype: cor_van_de_water     IM: [hidden email]
Tel: +1 408 383 7626        VoIP: +31 20 3987567 FWD# 25925
Tel: +91 (040)23117400 x203 XoIP: +31877841130

Please consider the environment before printing this e-mail.
-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On
Behalf Of Lee Hart
Sent: Saturday, February 07, 2009 10:02 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] OT: AC power to run a DMM

>> It isn't about footprint it is about using a sledge hammer to pound
>> in a thumbtack.

Jeff Shanab wrote:
> Trust me. The cost of our embedded linux boards are well under $50
> :-), The computing power of micro controllers has gone up while the
> power requirements for a linux embedded has gone down... one camera
> has a max power usage of 11W while serving up to 4 video streams, the
> web UI, and alarm array and a relay array, ssh etc.

OK, so it's a small sledgehammer. But it's still a hammer. Shouldn't you

push a thumbtack in with your thumb?

My Radio Shack 22-168A digital multimeter with RS-232 interface used 9v
at 7.5ma = 0.0675 watts to produce clear ASCII data. Is it progress to
leave the intelligence out of the meter to save a dollar, but then use a

a computer that requires 100's of times more power to interpret what it
says?

The meters in my old EVs were analog -- they needed *no* separate power
supply (they ran off the signal they were measuring, and drew only
microamps). The $10 digital LCD meters with the ICL7106 chip use less
than 1 ma -- we've had them for over 20 years now. Likewise, we've had
solar calculators that run on room ambient light, and watches that run
for a year on a tiny battery.

Designers *know* how to build low power electronics. They just don't
bother! There is still this attitude that power is free and unlimited --

use all you want! Stupid engineering is cheap and easy, and that's all
we want. But cheap and easy does not lead to good long-term solutions.

--
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in    --    Leonard Cohen
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net

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Is Linux practical for EV? [OT: AC power to run a DMM]

Greg Anderson
In reply to this post by Jeff Shanab
I've seen the Linux-vs.-Windows posts and the Linux-vs.-microcontroller
posts; quite frankly, given my background and area of comfort /
experience, I would prefer to go with an embedded linux board.

However, it seems like all of the pre-built components and free software I
have seen for EVs are all Windows-based.  My question is, is there useful
EV software available for Linux that I just haven't found yet, or would I
end up having to write everything myself if I went the linux route?

Don't get me wrong, it would be easy for me to code up some stuff that
runs on Linux, but I see that as quite a potential time-sink and
distraction from what I really need to do (which at this point is find a
donor car and start figuring out battery and engine design...)

Thanks,

     - Greg


> Trust me. The cost of our embedded linux boards are well under $50 :-),
> ...
> So what happens is you get to choose between writing everything yourself
> and the provided infrastructure and drivers the Linux has.
> As soon as you want to save to a usb drive or flash or have a display
> and not lose information during selection, it starts to make even more
> sense.


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Re: Is Linux practical for EV? [OT: AC power to run a DMM]

evan foss
On Sat, Feb 7, 2009 at 12:47 PM, Greg Anderson <[hidden email]> wrote:
> I've seen the Linux-vs.-Windows posts and the Linux-vs.-microcontroller
> posts; quite frankly, given my background and area of comfort /
> experience, I would prefer to go with an embedded linux board.
>
> However, it seems like all of the pre-built components and free software I
> have seen for EVs are all Windows-based.  My question is, is there useful
> EV software available for Linux that I just haven't found yet, or would I
> end up having to write everything myself if I went the linux route?

I have not seen any linux utilities specifically for electric cars. I
have seen data logging software for linux if that is what you are
looking for. I switched off of windows back in 1998. I am not
anti-linux, I am anti-bloat.

>
> Don't get me wrong, it would be easy for me to code up some stuff that
> runs on Linux, but I see that as quite a potential time-sink and
> distraction from what I really need to do (which at this point is find a
> donor car and start figuring out battery and engine design...)

That is probably the proper order.

>
> Thanks,
>
>     - Greg
>
>
>> Trust me. The cost of our embedded linux boards are well under $50 :-),
>> ...
>> So what happens is you get to choose between writing everything yourself
>> and the provided infrastructure and drivers the Linux has.
>> As soon as you want to save to a usb drive or flash or have a display
>> and not lose information during selection, it starts to make even more
>> sense.

You can write bad real time code on any platform.

>
>
> _______________________________________________
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>



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Re: Is Linux practical for EV? [OT: AC power to run a DMM]

Jukka Järvinen
FEVT uses in their Cell Control System (CCS, advanced BMS) embedded
Linux as main CPU. It supervises BMS functions that run on over 100
microcontrollers (if ~90 cells are installed) distributed all over
batteries through CAN network.

Sounds more complex than what it is. Due the topology it's extremely
reliable and powerfull battery manipulator.

If made in high volumes the generic hardware is not that expencive. Thou
basic shunting BMS is easier and cheaper to make. Life extensions and
other functions may pay off that difference. Not valid in all
applications. That I'm quite sure of.

Main functions of the whole thing is on the SW that runs on the Linux.
Designed for EVs but can be used almost anywhere.


-Jukka

evan foss kirjoitti:

> On Sat, Feb 7, 2009 at 12:47 PM, Greg Anderson <[hidden email]> wrote:
>> I've seen the Linux-vs.-Windows posts and the Linux-vs.-microcontroller
>> posts; quite frankly, given my background and area of comfort /
>> experience, I would prefer to go with an embedded linux board.
>>
>> However, it seems like all of the pre-built components and free software I
>> have seen for EVs are all Windows-based.  My question is, is there useful
>> EV software available for Linux that I just haven't found yet, or would I
>> end up having to write everything myself if I went the linux route?
>
> I have not seen any linux utilities specifically for electric cars. I
> have seen data logging software for linux if that is what you are
> looking for. I switched off of windows back in 1998. I am not
> anti-linux, I am anti-bloat.
>
>> Don't get me wrong, it would be easy for me to code up some stuff that
>> runs on Linux, but I see that as quite a potential time-sink and
>> distraction from what I really need to do (which at this point is find a
>> donor car and start figuring out battery and engine design...)
>
> That is probably the proper order.
>
>> Thanks,
>>
>>     - Greg
>>
>>
>>> Trust me. The cost of our embedded linux boards are well under $50 :-),
>>> ...
>>> So what happens is you get to choose between writing everything yourself
>>> and the provided infrastructure and drivers the Linux has.
>>> As soon as you want to save to a usb drive or flash or have a display
>>> and not lose information during selection, it starts to make even more
>>> sense.
>
> You can write bad real time code on any platform.
>
>>
>> _______________________________________________
>> General EVDL support: http://evdl.org/help/
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>>
>>
>
>
>

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Re: OT: AC power to run a DMM

Chuck Hursch-2
In reply to this post by evan foss
Doubtful he will get better.  He's at the end of the road (old
age / stroke).  Just keep him comfortable, and he would be happy
to know that his laptop is being used for an EV project - taking
data no less! (one of the things an engineer, as he was, really
loves).

----- Original Message -----
From: "evan foss" <[hidden email]>
To: "Electric Vehicle Discussion List" <[hidden email]>
Sent: Friday, February 06, 2009 4:12 PM
Subject: Re: [EVDL] OT: AC power to run a DMM


> Oops should have read more carefully. Sorry about that. I hope
your
> friend gets better.
>
> On Fri, Feb 6, 2009 at 6:39 PM, Chuck Hursch <[hidden email]>
wrote:
> > evan foss wrote:
> >> On Fri, Feb 6, 2009 at 9:53 AM, Jeff Shanab
> > <[hidden email]> wrote:
> >> >> Chuck Hursch wrote:
> >> >>> At this point, I'm leaning towards the 22-812.  Looks
like
> > a nice
> >> >>> meter.  I'll probably use zmeter from sourceforge.net to
> >> >>> interpret the RS-232 output (I'm planning on doing this
on
> > a
> >> >>> Linux variant - Ubuntu on the laptop I acquired a couple
of
> >> >>> months ago).
> >> >>
> >> >> That should work, though it ain't exactly elegant to use
a
> > linux
> >> >> computer for what should be a simple task.
> >> > <snip>
> >
> > All I've got right now for this little project is a laptop
given
> > from the estate of an EV friend who can no longer use it,
because
> > of health reasons.  Had only WinXP before, but I had it made
into
> > a multi-boot machine with Ubuntu Linux.  I'd much rather work
in
> > Linux and some C/C++/Java variant than Windoze.  I plan on
> > getting some kind of data stream working with the Linux
platform,
> > then at some point I'd be working into the small micros as
> > mentioned below.
> >
> > Unfortunately, yesterday I got tuned into the fact that this
> > laptop has no RS-232 port, only a USB port, so that may add a
> > level of complication.
> >> >
> >> > Where I work they have linux based computers on boards
that
> > are less
> >> > than 2" square and use power over ethernet for their
power. I
> > can ssh
> >> > into them and it contains a full file system and runs a
video
> > streaming
> >> > server, a web server for configuration, and other upnp
apps.
> > I was
> >> > really impressed with how scalable linux can be. Linux
also
> > makes
> >> > develop on desktop for a different target pretty easy. It
got
> > me
> >> > interested in linux mini computers like the gumstix and
> > uClinux and the
> >> > little ethernet port with a linux computer in it.
> >>
> >> It isn't about footprint it is about using a sledge hammer
to
> > pound in
> >> a thumbtack. I understand the motivation to use it though.
It
> > is easy
> >> and fast, the buzzword now is rapid prototyping but it is
more
> > than
> >> just a little overkill. I prefer typically in cases like
this
> > to start
> >> off doing it the way you are if the task is a large one and
> > after it
> >> works go back and redo with something more appropriate. It
is

> > just a
> >> question of taste and budget though.
> >> 68HC11 with gluechips $40
> >> Embedded linux kit >$100
> >>
> >> That said what you are doing is still cool.
> >>
> >> >
> >> > http://www.gumstix.com/               Cool periperials,
> > reasonable
> >> > price, Very Active (Note robostix)
> >> >
> >> > http://www.uclinux.org/ucsimm/   slow web, old project,
not
> > so active
> >> >
> >> > http://www.picotux.com/               OMG!
> >> >
> >> > Perhaps one of these would work well.
> >> > I had written a C program to read from the meter, but I
can't

> > find it :-(
> >> >
> >> > _______________________________________________
> >> > General EVDL support: http://evdl.org/help/
> >> > Usage guidelines: http://evdl.org/help/index.html#conv
> >> > Archives: http://evdl.org/archive/
> >> > Subscription options:
> > http://lists.sjsu.edu/mailman/listinfo/ev
> >> >
> >> >
> >>
> >>
> >>
> >> --
> >> http://www.coe.neu.edu/~efoss/
> >> http://evanfoss.googlepages.com/
> >>
> >> _______________________________________________
> >> General EVDL support: http://evdl.org/help/
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> >
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> >
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Re: OT: AC power to run a DMM

Chuck Hursch-2
In reply to this post by Cor van de Water
Cor van de Water wrote:

> Chuck Hursch wrote:
> >Unfortunately, yesterday I got tuned into the fact that this
> >laptop has no RS-232 port, only a USB port, so that may add a
> >level of complication.
>
> Almost no newer laptop has an RS-232 port these days.
> No problem, just buy an RS-232 dongle, this is a cable
> that has a USB-RS232 converter in its plug and a few feet
> of USB cable to plug into your laptop.
> They are plentiful and cheap on Ebay though make sure you
> save the install disk and try to see beforehand if it will
> work on Linux or check if a driver has been made available
> for the particular dongle.
> The cheapest cable I found had a HL-340 and I had to reinstall
> the driver when my Windows box crashed. Took me almost an hour
> to find a driver again without requiring a subscription to a
> driver database site.
> Note: don't be afraid to download the original driver from
> the Chinese manufacturer's website.

Yes, I am aware there are RS-232 -> USB converters.  But I just
checked zmeter at sourceforge (zmeter was an app I was
considering to read the output from the RS DMM), and there is no
option to read from a USB port, only serial (RS-232) port.  I
don't know what is involved in setting that up to read from a USB
port.  I know C and the zmeter source code I believe is
available.  So the USB angle is what I have to become familiar
with.

Thanks.

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