Testing machine errors with MCU based device

[Igor]

Hi.

I want to monitor state of machine ( e.g. pump state, pressure, water
level etc. ) with my MCU based controller/device.

Would it be enough to use A/D converter or do i need D/A converter ?
Based on this i have to select MCU. Most of them have A/D converter but
i dont know if i need D/A for such task..

regards!

[petrus bitbyter]

"Igor" <ig...@com.net> schreef in bericht news:kmada3$u8l$1...@l01news1.ot.hr...

You can't drop an mcu in a water tank to measure the water level :) For the
functions you need you'll have to find out what sensors you need. Some may
be easy to find or to build, others may be difficult and expensive. Some
sensors may look like very good in the labaratory but may be useless in an
(electrically) noisy environment. The properties of the mcu required depend
highly on the properties of the sensors. Nevertheless it seems very unlikely
that you need a DA-converter. Once you know your requirements, you have a
large number of mcus to make your choice, though I think you'd better look
for a complete system like PIC-stamp, Arduino or even Raspberry pi.

petrus bitbyter

[Uncle Steve]

Your sensors will provide inputs to the computer, and if they encode
their readings in analog voltages, you will need A/D conversion. If
you have something like a mechanical valve that is to control the rate
of flow and it maps voltage levels to valve state, you will need D/A
conversion to set that with the computer.


Regards,

Uncle Steve

--
There should be a special word in the English language to identify
people who create problems and then turn around and offer up their own
tailor-made bogus non-solutions designed to completely avoid the root
causes of the situation under consideration. 'Traitor' might be a
good choice, but lacks the requisite specificity. One of the problems
with contemporary English is it lacks many such words that would
otherwise categorically identify certain kinds of person, place, or
thing -- making it difficult or impossible to think analytically about
such objects. These shortcomings of the English lexicon are
representative of Orwellian linguistics at work in the real world.

[whit3rd]

On Tuesday, May 7, 2013 1:11:52 AM UTC-7, Igor wrote:

> I want to monitor state of machine ( e.g. pump state, pressure, water
> level etc. ) with my MCU based controller/device.
>
> Would it be enough to use A/D converter or do i need D/A converter ?

> Based on this i have to select MCU.

Any microcontroller can implement D/A converter functions with
pulse width modulation. Whether this is sufficient for your needs,
depends on ... your needs.

[Tim Wescott]

"I want to build a building. Would it be enough to have wood, or should
I have some metal, too?"

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

[Uwe Hercksen]

Igor schrieb:

Hello,

an A/D converter is useful for input of sensor values, a D/A would be
used for output. As long as you dont need analog output, you dont need D/A.

Bye

[Igor]

It looks like we seem to have misunderstood.
Machine that i want to check has all necessary sensors built in.
My job is to send this analog or digital signal, from those sensors,to
MCU device controller.

What Im not sure of is, would it be enough to use just A/D pin input.
As far as i know most of such machines use some kind of analog control,
so i dont think i have to use digital output.

Bottom line, i have to take signal from those sensors and process them.
If this signal is in analog value, no problem but if the signal is in
digital format, what can i do then ?

I would have to detect protocol and encoding using by this sensor etc... ?

[petrus bitbyter]

"Igor" <ig...@com.net> schreef in bericht news:kmi9ou$kch$1...@l01news1.ot.hr...

So you heve the required sensors in place and at your disposal already?
Well, the next step is to map out their properties. Including place,
protocol, signal type(s), boudaries and everything you need to know to
calculate the info you need to present to the mcu. As my crystal ball in
defective once more I can only speculate about your requirements.

petrus bitbyter

[Igor]

--------------------
One example would be to process error data from frequency inverter like
Eaton. This regulator is used to control 3phase machine and it has
standard inputs where i can connect my "error logging device".

I would like to collect those data and save them to MCU.
What would be the simplest way to do this ?

http://www.moeller.net/en/products_solutions/motor_applications/switch_protect/frequency_inverter/frequency_inverter_mmax/index.jsp
-------------------

[Rich Webb]

You need to decide which input/output interfaces, measurable device
parameters, or analog controls are of interest.

For each of these, determine an appropriate means of measurement,
control, or communications.

Then design a system.

The example that you cite above has:
6 digital control inputs (24 V DC, adjustable logic)
1 digital output (transistor, 24 V DC, 50 mA)
2 analog inputs (0�10 V DC / 0/4�20 mA, adjustable)
1 analog output (0�10 V)
2 relays (1 x N/O, 1 x C/O, 230 V AC, 2 A)
Serial interface (RS485 / Modbus RTU)
Fieldbus communication (PROFIBUS, CANopen, DeviceNet) (optional)

From these, you decide which ones are meaningful. Then you research
each interface, generally in cooperation with the equipment's
application engineers and the end-use facility engineers. Then you
implement the interface in a way that is practical, economical, and in
compliance with applicable standards.