Looking for multichannel PID controller IC

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is there a PID controller available in an off-the shelf
IC package for integration on a PCB?

or, what would be the cheapest way to implement 16 channels of
PID temperature control (RTD in -> PWM out)?

could one get a 16 channel PID temperature controller from
Omega or Watlow for <~2k$US?

tia!

Re: Looking for multichannel PID controller IC
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Look at 'Microchips' website. They have many development boards too.
If you do not find exactly what you want, send me some private email.
We do lots of embedded control development for other companies....


James



Re: Looking for multichannel PID controller IC

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Or Atmel, or Silicon Labs, or Infineon, or Philips, or, or, or.

--

Tim Wescott
Wescott Design Services
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Re: Looking for multichannel PID controller IC

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The cheapest way for a hobbyist or a product is to use a
microcontroller, an ADC, and a driver with some PID software.  Are you
doing a one-off, a hobby project, or is this for a product?

See the various articles on my website for guidance on implementing your
PID controllers once you've found your processor, or contact me.

--

Tim Wescott
Wescott Design Services
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Re: Looking for multichannel PID controller IC
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Thanks for info, but would like a dedicated PID controller IC like
those dedicated motion controller IC's. This would be for a
medium-volume embedded SBC-type product.

I am familiar with the motion controller IC's from some time ago,
but haven't sufficiently kept up with the IC data book barrage lately to know
if there are similar offerings for a generic PID controller IC.

tia!

Re: Looking for multichannel PID controller IC

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Look at the chips from Performance Motion Devices:
http://www.pmdcorp.com /

--
Jim McGinnis

Re: Looking for multichannel PID controller IC
snipped-for-privacy@yahoo.com (perfb) wrote in message
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snip

I don't know of any off the shelf pid controller solutions. If there
were I doubt I'd get as much consulting business as I do.

Doing a pid controller in a micro is pretty simple. I've done several
variations on pid temperature controllers. Typically the cycle time is
pretty slow, so doing a controller in C, using floating point math is
usually fast enough.

I've a bit of experience with Microchip PICs in these sorts of
applications, and development has been pretty easy (though about any
decent microcontroller would do). Microchip even has some high end 18F
series parts with 16 analog inputs (18F8720. etc.). You could add an
analog mux to other smaller microcontrollers.

If the thought of writing code from scratch for a microcontroller
fills you with dread, consider hiring somebody to do that part for
you. If you need more than 10 of these things, you should be able to
hire someone to do the initial PID control loop design for you, and
still come in under what it would cost you to buy a commercial
product.

mark

Re: Looking for multichannel PID controller IC

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Really a microcontroller is about as close to an off-the-shelf PID
controller as you could get -- particularly for a temperature controller
where the speeds will be fairly slow.  I doubt that there is a dedicated
"PID" controller chip that you could design that would be able to do
anything you couldn't do cheaper and better with a microprocessor and
some software.

In fact, for dedicated motor control the market seems to be swinging in
the direction of small DSP chips with software, as well.

--

Tim Wescott
Wescott Design Services
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Re: Looking for multichannel PID controller IC

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Do you have issues with software (medical, safety critical, etc) ?

--
Mike Page BEng(Hons) MIEE           www.eclectic-web.co.uk
Quiet! Tony's battling the forces of conservatism, whoever we are.

Re: Looking for multichannel PID controller IC
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Sorry for plugging my own company but you asked.
The CLS or MLS family from Watlow would be one method;
http://www.watlow.com/products/controllers/co_auto.cfm#2loop

I'm in R&D so I don't know pricing but you can get that pretty easily
on the phone.  If you are only looking for one unit I see these on
Ebay periodically.  Omega probably has something similar.

If this is OEM stuff we may have some custom off the shelf solutions
for you.

Again I apologize for doing a commercial.

Bill Schuh
Watlow

Re: Looking for multichannel PID controller IC

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I generally agree with others, in that I'm not aware of some IC solution to
this.  In the past, I've just developed appropriate code.  But I can suggest
some questions and considerations.

There are several factors which can be very important for PID control loops.
One is simply keeping your "observation" to "control" timing both short and
repeatable.  There is almost nothing worse than having a long lag time between
making a measurement and outputting a control, where "long" is a time related to
response of your system.  And having variability in that timing only makes it
very much harder to find good PID parameters that will work, consistently.

I like to imagine having a long, thin, all-too-flexible bamboo pole and standing
on the ground trying to poke it through a tiny hole in a bird house from some
distance.  The length of my pole is the time delay from observation to control
output and varying that time is like having a pole that is constantly changing
in length.  If you want to make this easy, you want a short pole and one that
doesn't change it's length.  If you want to make it really hard, get a long pole
and/or make it vary a lot, too.

Tighten up your timing as much as you can and work on the variability, too.
Both are important for clean PID control and it will save anguish in the end.
(That is, if you are forced to write this yourself or you get someone else to do
it for you.)

...

In general, by the way, how fast is your RTD and the system response to closed
loop control?  Why are you using an RTD?  Is it because you have a much wider
temperature range than a thermistor, for example, could be used?  (RTDs
generally are lower sensitivity, but better linearity and operable over wider
temp ranges.)

Jon

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