4-20 ma output
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Posts: 46,084
Take the voltage reading off of a precision 250 ohm resistor into the A/D.
That will give you 1-5V over the 4-20mA range.
Mark
Original Message
From: Ricky Konvicka [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=rLKfKKovOFQ2oz9CbwfBwqs_Ctrxz_TUM3Qdsx3DEac762ktScfc5NbXNpqvS4f1X0RNikBQ1cqqTZ_-pUs2xhYGcDfm]ricky@m...[/url
Sent: Monday, March 18, 2002 12:12 PM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] 4-20 ma output
Can Someone tell me where I might find some information on taking a 4-20 ma
reading, converting it to a voltage and feeding in to an A/D. Thanks!
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That will give you 1-5V over the 4-20mA range.
Mark
Original Message
From: Ricky Konvicka [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=rLKfKKovOFQ2oz9CbwfBwqs_Ctrxz_TUM3Qdsx3DEac762ktScfc5NbXNpqvS4f1X0RNikBQ1cqqTZ_-pUs2xhYGcDfm]ricky@m...[/url
Sent: Monday, March 18, 2002 12:12 PM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] 4-20 ma output
Can Someone tell me where I might find some information on taking a 4-20 ma
reading, converting it to a voltage and feeding in to an A/D. Thanks!
[noparse][[/noparse]Non-text portions of this message have been removed]
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Comments
5V. 205 ohms will get you about 4.096V. You might need an op amp buffer
or else you'll need to worry about ground references and loading with
the A/D's input impedance. The idea is to measure the differential
voltage across the resistor.
Al Williams
AWC
* 8 channels of PWM
http://www.al-williams.com/awce/pak5.htm
>
Original Message
> From: Ricky Konvicka [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=yapuRYSPBlreFj6e7pS4XsI6Mrs8weRlfd1p6pZVJziIwL97pXPLOIImjqmSYzTRJ6geipuvHEkXbmuoxghy2hAm]ricky@m...[/url
> Sent: Monday, March 18, 2002 12:12 PM
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] 4-20 ma output
>
>
> Can Someone tell me where I might find some information on
> taking a 4-20 ma reading, converting it to a voltage and
> feeding in to an A/D. Thanks!
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
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> Subject and Body of the message will be ignored.
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reading, converting it to a voltage and feeding in to an A/D. Thanks!
[noparse][[/noparse]Non-text portions of this message have been removed]
that has the 4-20ma. I ran it straight into a 12 bit A/D subtracted 825 to
compensate for the 4 ma offset. Then divided by 22 and wala. Ph control
with a stamp chip. Thanks again!
Original Message
From: "Al Williams" <alw@a...>
To: <basicstamps@yahoogroups.com>
Sent: Monday, March 18, 2002 8:25 AM
Subject: RE: [noparse][[/noparse]basicstamps] 4-20 ma output
> All you need is a resistor. A 250 ohm 1% resistor will convert 20mA to
> 5V. 205 ohms will get you about 4.096V. You might need an op amp buffer
> or else you'll need to worry about ground references and loading with
> the A/D's input impedance. The idea is to measure the differential
> voltage across the resistor.
>
> Al Williams
> AWC
> * 8 channels of PWM
> http://www.al-williams.com/awce/pak5.htm
>
>
>
>
>
> >
Original Message
> > From: Ricky Konvicka [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=xtNGwMPEz8lSVgoDd86vrTgYu24q55iNXnw_IyF6VQYjlNbG6kcWDvZNsjZFG6gECsyZKKW9ctFAvXig84UVG0w]ricky@m...[/url
> > Sent: Monday, March 18, 2002 12:12 PM
> > To: basicstamps@yahoogroups.com
> > Subject: [noparse][[/noparse]basicstamps] 4-20 ma output
> >
> >
> > Can Someone tell me where I might find some information on
> > taking a 4-20 ma reading, converting it to a voltage and
> > feeding in to an A/D. Thanks!
> >
> >
> > [noparse][[/noparse]Non-text portions of this message have been removed]
> >
> >
> > To UNSUBSCRIBE, just send mail to:
> > basicstamps-unsubscribe@yahoogroups.com
> > from the same email address that you subscribed. Text in the
> > Subject and Body of the message will be ignored.
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> > http://docs.yahoo.com/info/terms/
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