well we used a resistor 250 ohm and we supplied the sensor with 12v and then got a reading of 0.985 . so i guess this is the reading of the pressure when 1v=mA =0 bar . but then should't be reading the atmospheric pressure because it can not really be 0 bar ?

The sensor may read absolute pressure and be set to give 4mA at ambient atmospheric pressure.

EDIT:
Read this clip from the datasheet.

 

This thread is getting long and I still lack overview of what the measurement / signal will be used for?

Because if it is remote viewing, then a standard adjustable LED or LCD panel instrument might be the solution?

we will read it through ETAS model

The sensor may read absolute pressure and be set to give 4mA at ambient atmospheric pressure.

if i remove the resistors i get reading of the voltage supply

 

if i remove the resistors i get reading of the voltage supply

You will.
Use a 250R load

 

if i remove the resistors i get reading of the voltage supply

You will.
Use a 250R load

?
and the reading i get is 0.985 this is voltage at atmospheric pressure right? which = 101,325 pascals right?

https://www.google.nl/webhp?sourceid=chrome-instant&ion=1&ie=UTF-8&rct=j#q=atmospheric+pressure

 

if i remove the resistors i get reading of the voltage supply

You will.
Use a 250R load

so the main question now is 0 bar =4mA is the atmospheric pressure ?? because the reading which i get i when i put 250ohm and 12v as power supply the reading is 0.985 =4mA = 0 bar

 

It's calibrated that way

 

It's calibrated that way

sorry but what dose that mean ?

 

It does not read atmospheric pressure.
It reads the pressure applied to it.

 

Think like this.
Atmospheric pressure to the sensor is 0 bar

 

Think like this.
Atmospheric pressure to the sensor is 0 bar

thanks i get it now , but one more queation i am using 250ohm now with 12 v as a power supply . what resistor should i use if i am supplying the sensor with 30v , i mean how i can know what resistor i use every time?

 

You did not read the link I provided.
It has an answer

 

thanks i get it now , but one more queation i am using 250ohm now with 12 v as a power supply . what resistor should i use if i am supplying the sensor with 30v , i mean how i can know what resistor i use every time?

It is 250R for 10V thru 30v

 

In fact, the minimum voltage must be 15 volts.

The pressure transmitter requires at least 10 Volt and the load resistance of 250 Ohm takes the last 5 Volt.

 

In fact, the minimum voltage must be 15 volts.

The pressure transmitter requires at least 10 Volt and the load resistance of 250 Ohm takes the last 5 Volt.

In my experience the Vmin supply of 10V is able to deliver 20mA into a 250R load.

 

I am using 17VDC

 

I am using 17VDC

no matter what type of resistor i use or what voltage i apply between 10v and 30v i always get almost a fixed reading of voltage . so now i think my reading are right and i get how the pressure works , thanks a lot guys you were really helpful today


one more question do you know guys what formula i can use to transfer the output reading of this voltage sensor into a pressure reading ?

 

one more question do you know guys what formula i can use to transfer the output reading of this voltage sensor into a pressure reading ?

How do you wish to display the reading ?

 

How do you wish to display the reading ?

in kPa

 

Again how you wish to display the Pressure?
On an LCD or by LEDs

 

in kPa

As1 bar =100kpa, so you have a range of 0kpa thru 600kpa
If you use a 250R resistor , at 4mA == 0bar will be 1v.
at 20mA = = 6bar will be 5v.

So 4v change is 6bar change or 600kpa.

Subtract 1v from your meter reading and then multiply the rmainder by 1.5 to give a bar value.
For a kpa value multiply this by 100.

Examples:

Meter reads 3v, sub 1v then, 2v *1.5 = 3bar = 300kpa.
5v -1v = 4v *1.5 = 6 bar
1v-1v =0 bar

OK.??