I have now received a senstronic transducer/transmitter that i want to connect to my arduino board.
Going to run it on external power because of the input needed.
I need to connect the ground and signal to the arduino? And the Supply +ve and ground to external power?
the output is 0-5V 1-20mah. Possible to get useful readings out of it?
Please school me on this. 
Karl
How about a link to the manufactures data sheet since you have the part in hand. Then nobody has to guess at the exact specs...
How about a resistor to 5V on one side, the the other side to ground and the middle to an arduino AD port. Simple enough? Since you did not say which Arduino I will assume 5V. Try a 1K -- see what happens...
I presume you can plug it into water mains or something to measure pressure or whatever it is -- gas tank?
There are lots of A to D examples in the standard version 22 IDE.
Good Luck.
Here is the relevant information i got from the supplyer. Do i need to connect 2 and 4 to the power supply and 1 and 4 to the arduino?
How do i read the data. Is it possible to read out the rawdata and fiddling with some math to get proper numbers?
The transducer is going to be used in an arduino based underwater ROV. I can be able to test/calibrate using compressed air that i have at home.
Karl
Looking at the top name plate information picture you posted, there appears to be three different outputs avalible, 4-20ma current loop, 0-5vdc and 1-6vdc. However without a detailed datasheet or OEM manual it's not clear how one would wire up for the three different output options. Be careful as any wiring method that applies more then +5vdc to a Arduino pin will damage your chip.
Normally if one knows the sensor's manufacturer's name and model number a google search will come up with a datasheet or users manual, but you have provided neither and the E-bay listing also doesn't supply that information.
Lefty
So which one is it...
http://www.senstronics.com/catalog/products.php
It has to be type A. It says 4-20 mah on the transucer itself.
Have fiddled a bit around with it.
I connected 12v adapter to pin 2 and 4. And an arduino duemilanove to pin4 and pin1.
Used a simple code to se if i got any numbers out of it. And i did. reading vary from 23-25. Going to search for a adapter so i can give it some air up to 10bar. then, if im correct i would get reading about 165.
int pressurePin = 0;
float var;
void setup() {
Serial.begin(9600);
pinMode(pressurePin, INPUT);
}
void loop() {
var = analogRead(pressurePin);
Serial.println(var, DEC);
delay(1000);
}