Quote Originally Posted by HenrikOlsson View Post
Hi,
If that what it says then that's how it is. I didn't check the datasheet and I've never personally used a PIC where only the +Vref is available. Now I know they exist as well, thank you!

Then it gets trickier, one way is to use some analog circuitry to first subtracst 1V from the signal and then amplify it with a gain 1.25, that will give you 0-5V output. An easier way is probably to get a PIC which has it's -Vref available to the outside.

There are IC's available specifically for converting current loops to voltage, here's a MAXIM app note showing one.

But again, what kind of resolution do you really need? Do you have a datasheet for the transducer you're using?

/Henrik.

hai HENRIK,

THANKS FOR YOUR KIND HELP.For now i don't have the datasheet,but give some time ill find the datasheet and forward to you.Actually i want to read the 4-20 mA from a transduser with the accuracy of 0.1% and the resolution is 0.0000,the transduser has the accuracy of 0.05% and the range is 0-100,000psi this the maximum that we have.so if i manage to do the project,then i can use the same for all the other transduser with better accuracy.some are 0-5v and few are 0-10v which will be easy to do as you said.

THANKS and REGARDS,
PUGAL.