Problem with pressure transducer

[spintinas]

Hello, my problem is related to pressure transducer. I have a pressure transducer Data Instruments (now Honeywell) AB model 25 psi. Datasheet is here: https://stevenengineering.com/tech_support/PDFs/31DTMAIN.pdf . (My transducer in datasheet is first, AB model). Problem is, that when I power this transducer from usb connector, transducer didn't work correctly. When there is no pressure, I get the 2.5V DC voltage in my multimeter, but according to datasheet Zero Output is 0 + 5 mV. Also, when I pressure transducer there is no change, anyway 2.5V from transducer. In my opinion power source is good, because voltage between Excitation+ and Excitation- is 5V. So, maybe anything of you know what problem it can be?

 

[Pommie]

Your link doesn't work. Could it be that you're reading atmospheric pressure? Are you saying that Zero is 14psi? 14psi on a 25psi transducer would be close to 2.5V.

Mike.

 

[JimB]

Looking at the datasheet, you should apply the 5v excitation to the red (+) and black (-) wires, and measure the output between the green (signal +) and white (signal -) wires.

You are probably measuring between the black and one of the green or white wires, where I would expect to see half the excitation voltage, ie 2.5v in your case.

JimB

 

[KeepItSimpleStupid]

Pressure is very wierd. What is the actual model of the sensor. e.f, the Reference ( 1 of 3). What are you trying to measure? What do you expect.

Output an input Z in parallel might put ti close to 0.1A on your USB 5V.

It's probably a bridge transducer, so you need to make a differential measurement,

Absolute and guage pressure will surely mess up your day.

 

[spintinas]

Pressure is very wierd. What is the actual model of the sensor. e.f, the Reference ( 1 of 3). What are you trying to measure? What do you expect.

Output an input Z in parallel might put ti close to 0.1A on your USB 5V.

It's probably a bridge transducer, so you need to make a differential measurement,

Absolute and guage pressure will surely mess up your day.

Pressure transducer is absolute. I try to measure pressure from pump used for blood pressure monitors, so the applied pressure for transducer is about 0-200mmHg (0-4 psi), my transducer range is 0-25psi. So, I think i might see voltages between, maybe 0-20mV.
Maybe, there are so options to perform more precise measurements with this transducer?

 

[spintinas]

So, now I check again, and I see that voltage between data signals is ~65mV, in datahsheet i saw, that my transducer is absolute pressure. So, when I try to measure pressure from my blood pressure pump, I see voltage 65mV, which equal to 14,7 psi (atmospheric pressure). 25psi - 100mV, 14,7psi ~50mV, i came to conclusion, that transducer works correctly, but now I have a question, how to perform pressure measurement with this transducer? It's there some ways to callibrate them or any onther options? When I apply some pressure on transducer, still I get value of 65mV (atmospheric pressure).

 

[ronsimpson]

It's there some ways to

You probably need two transducers. One to look at the blood pressure and one to look at room pressure. (subtract readings)
I think you can connect the transducers together so the voltage adds or subtracts.

 

[KeepItSimpleStupid]

Also remember that barometric pressure reported by the weather bureau is normalized to sea level.