# Re: [EVDL] OT: AC power to run a DMM



## EVDL List (Jul 27, 2007)

*Re: [EVDL] OT: AC power to run a DMM*

> 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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## EVDL List (Jul 27, 2007)

*Re: [EVDL] OT: AC power to run a DMM*



> Jeff Shanab wrote:
> >> Lee said
> > ...
> >> I've used several brands of these meters with "PC compatible" RS-232
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] OT: AC power to run a DMM*



> Lee Hart wrote:
> > Jeff Shanab wrote:
> > >> Lee said
> > > ...
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] OT: AC power to run a DMM*



> 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
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] OT: AC power to run a DMM*



> Lee Hart <[email protected]> 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
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] OT: AC power to run a DMM*



> Chuck Hursch <[email protected]> wrote:
> 
> Most of those small inverters run around a quarter amp (3 or 4 watts) with
> no load.
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] OT: AC power to run a DMM*



> > 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
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] OT: AC power to run a DMM*



> Jeff Shanab <[email protected]> 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
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] OT: AC power to run a DMM*



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


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] OT: AC power to run a DMM*

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.



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


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] OT: AC power to run a DMM*

Oops should have read more carefully. Sorry about that. I hope your
friend gets better.



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


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] OT: AC power to run a DMM*

>
>


> Jeff Shanab <[email protected]> wrote:
> >
> >>> >> Chuck Hursch wrote:
> >>>
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] OT: AC power to run a DMM*



> 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.
> ...


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## EVDL List (Jul 27, 2007)

*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
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] OT: AC power to run a DMM*

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: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [email protected]
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: [email protected] [mailto:[email protected]] 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
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] OT: AC power to run a DMM*

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" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
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 <[email protected]>


> wrote:
> > > evan foss
> 
> 
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] OT: AC power to run a DMM*



> 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
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] OT: AC power to run a DMM*

As long as you use the standard ports and interfaces 
of the operating system you run this on, it should
not be needed to learn USB because as soon as you
plug the dongle it and it is recognised by the
driver on the computer, an additional COMx port is
created, x being a number associated to whatever
USB port is used. As long as you plug the dongle
into the same USB, it gets the same port number.
Plug it into a different USB port and it becomes
a different COM port.

Use the standard operating system calls to access
the COM port and you are good to go, no matter
whether it is a physical RS-232 on the computer
or it is connected via USB.

Success,

Cor van de Water
Director HW & Systems Architecture Group
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [email protected]
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: [email protected] [mailto:[email protected]] On
Behalf Of Chuck Hursch
Sent: Sunday, February 08, 2009 4:48 AM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] OT: AC power to run a DMM



> 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
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] OT: AC power to run a DMM*

I think I may of missed the beginning of this thread. I thought he 
wanted to collect the data. And we were discussing options for that.
I am a believer in keeping it as simple as possible(but I am not good at 
it, yet), so forgive me if I lead this thread astray in my enthusiasm!

>>> 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
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] OT: AC power to run a DMM*



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


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] OT: AC power to run a DMM*



> Chuck Hursch wrote:
> 
> > Yes, I am aware there are RS-232 -> USB converters. But I just
> > checked zmeter at sourceforge (zmeter was an app I was
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] OT: AC power to run a DMM*



> Lee Hart wrote:
> 
> > The newer meters that send encoded segment data are undocumented. *They*
> > are the ones that you can't use for anything else without extensive
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] OT: AC power to run a DMM*

Hi Cor, et-al,

It looks like /dev/ttyUSB* will access a USB port for me on
Linux. One task is to determine which USB port it will be, and I
would assume that would have to be done programmatically somehow.
I suppose I could assume I'm always going into the same USB port,
and hardwire it for now.

I thought zmeter (http://zmeter.sourceforge.net/) for the RS
22-812 DMM (the one I'm proposing to buy) had the source code on
hand. I think what I was actually looking at in terms of C
source was http://www.linuxtoys.org/dvm/dvm.html for the 22-168.
This source is set up to use the RS-232 serial port, so I wonder
if I should still use the tbuf struct and the DTR-set below that,
and somehow it would all map correctly to a USB port through the
correct driver. I would think that would be a bit much to hope
for, but maybe it works that way, the USB driver taking care of
things. Somewhere else I saw the code snippet to interpret the
22-812's DMM's display segments into usable output, so I would
have to combine the 22-168 setup code and the 22-812 code. The
22-812 code source may be in the zmeter sourceforge download, but
I haven't seen it yet.

Getting the voltage versus time would be Baby Step 1. As Baby
Step 2 I would like to be able to switch the DMM between reading
the battery pack voltage and the charge current, so I have both
data being read into the computer within a second or two. In a
discussion with Roger Stockton that I had in late 2006, he
explained briefly his battery scanning setup where he was using
some CMOS logic chips and PhotoMOS relays. That sounds like a
lot more than I would need for Baby Step 2, but somehow I need to
switch that DMM to read amps (I envision just scaling off of a
shunt). There would have to be something between the DMM and the
charging wires that the computer could control, and the ? is what
is that? That would likely be directed off a second USB port.

I'm certainly wanting to get to the dedicated Stamps and whatnot
for a more permanent setup. That stuff looks like a lot of fun,
although probably one heck of a time sink. If I get there, I
envision a (bluetooth) network in the car, reading voltages and
charge current for data logging and display, both in the car and
up in the apt (via WiFi or somesuch). Baby steps first...

Thanks,
Chuck

----- Original Message ----- 
From: "Cor van de Water" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Saturday, February 07, 2009 4:42 PM
Subject: Re: [EVDL] OT: AC power to run a DMM


> As long as you use the standard ports and interfaces
> of the operating system you run this on, it should
> not be needed to learn USB because as soon as you
> plug the dongle it and it is recognised by the
> driver on the computer, an additional COMx port is
> created, x being a number associated to whatever
> USB port is used. As long as you plug the dongle
> into the same USB, it gets the same port number.
> Plug it into a different USB port and it becomes
> a different COM port.
>
> Use the standard operating system calls to access
> the COM port and you are good to go, no matter
> whether it is a physical RS-232 on the computer
> or it is connected via USB.
>
> Success,
>
> Cor van de Water
> Director HW & Systems Architecture Group
> Proxim Wireless Corporation http://www.proxim.com
> Email: [email protected] Private: http://www.cvandewater.com
> Skype: cor_van_de_water IM: [email protected]
> 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: [email protected]
[mailto:[email protected]] On
> Behalf Of Chuck Hursch
> Sent: Sunday, February 08, 2009 4:48 AM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] OT: AC power to run a DMM
>


> > 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
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] OT: AC power to run a DMM*



> Chuck Hursch wrote:
> 
> > I thought zmeter (http://zmeter.sourceforge.net/) for the RS
> > 22-812 DMM (the one I'm proposing to buy) had the source code on
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] OT: AC power to run a DMM*



> Chuck Hursch wrote:
> > I thought zmeter (http://zmeter.sourceforge.net/) for the RS 22-812
> > DMM (the one I'm proposing to buy) had the source code on hand. I
> > think what I was actually looking at in terms of C source was
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] OT: AC power to run a DMM*



> Lee Hart wrote:
> >> The newer meters that send encoded segment data are undocumented.
> 
> Tom Parker wrote:
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] OT: AC power to run a DMM*

>


> > Chuck Hursch wrote:
> >> I thought zmeter (http://zmeter.sourceforge.net/) for the RS 22-812
> >> DMM (the one I'm proposing to buy) had the source code on hand. I
> >> think what I was actually looking at in terms of C source was
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] OT: AC power to run a DMM*



> Lee Hart wrote:
> > > somehow I need to switch that DMM to read amps (I envision
> just
> > > scaling off of a shunt). There would have to be something
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] OT: AC power to run a DMM*

I was doing a project for work and read your little rundown of the old
ICM7xxx series chips here and though "I wonder where they went from
there."
Any way intersil now makes a nicer version HI-7159A which is really nice.
http://www.intersil.com/cda/deviceinfo/0,0,HI-7159A,0.html




> Lee Hart <[email protected]> wrote:
> > Cor van de Water wrote:
> >> Which chip is used in that DMM?
> >> Can't it be switched between outputing
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] OT: AC power to run a DMM*



> Chuck Hursch wrote:
> > Regarding the millivolts scale mentioned above, won't just having
> > the meter in the auto-range mode handle both the full pack
> > voltage reading and the millivolt reading from the shunt for
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] OT: AC power to run a DMM*



> evan foss wrote:
> > I was doing a project for work and read your little rundown of the old
> > ICM7xxx series chips here and thought "I wonder where they went from
> > there."
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] OT: AC power to run a DMM*



> Lee Hart <[email protected]> wrote:
> > evan foss wrote:
> >> I was doing a project for work and read your little rundown of the old
> >> ICM7xxx series chips here and thought "I wonder where they went from
> ...


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