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[on:]

Hi!

as you can see in the subject im  searching help at least for my "little" project.


to understand what im trying to do:

i want a small processing unit with a lcd what acting like a terminal.

the sensor has acually a 4-20mAh output, is it possible to work directly on arduino with this output?
if not,  there is a sensor available with 0-4,5V output <- this should go with the digital input from the arduino.

i want a touch lcd on it where i can programm a menu with buttons.
on a button click the ardunio should record the values from the sensor to a sd card.

after collecting some records it should be possible to send the data via bluetooth or wifi? to a pc?!

can someone say if this is possible  and what i need for this?

i found for exsample http://www.adafruit.com/products/330 this lcd,  whould it be possible to add bluetooth and a option for reading a sensor?

hope you can help me an sorry for my ultra bad english

[Reply #1 on:]

the sensor has acually a 4-20mAh output

Not likely, since only batteries have amp-hour ratings.

The sensor might have a 4 to 20 mA output, but that is not really relevant, since current is pulled, not pushed.

The voltage that the sensor outputs is much more important.

can someone say if this is possible  and what i need for this?

Yes it is. You've already listed everything you'd need.

[Reply #2 on:]

The sensor might have a 4 to 20 mA output, but that is not really relevant, since current is pulled, not pushed.

The voltage that the sensor outputs is much more important.

With this type of sensor, the current represents the quantity being sensed. The voltage in the circuit is irrelevant. It's done this way so that changes in the resistance of the cables does not affect the readings. The display devices used with these sensors are designed to measure the current and use that, suitably scaled, to drive the display.

[Reply #3 on:]

With this type of sensor, the current represents the quantity being sensed.

What type of sensor is that?

[Reply #4 on:]

What type of sensor is that?

The OP mentioned a 4-20mA sensor. They're commonly used in industrial control systems for temperature, pressure, all sorts of things.

http://en.wikipedia.org/wiki/4-20mA

[Reply #5 on:]

hi, thanks for reply

here a data sheet of a similar one.

http://www.tecsis.de/filestore.aspx/de708.pdf?pool=website&type=file&id=37db5fa0-880e-48df-b247-c7c5eb785348&lang=en&filetype=default

[Reply #6 on:]

  Per the datasheet you need a 8 to 30 volt power supply in series with your sensor. You then would need a resistor in series with the PS and sensor to measure voltage and calculate current. I calculate a 250 ohm resistor will give you 5 volts at 20ma. You may want to set-up something to protect your Arduino in case of failure so that the voltage will never exceed 5 volts.


Mark

[Reply #7 on:]

If you have the choice, the 0-5V version of the pressure sensor might be a better one for interfacing with an Arduino.