The Industrial Raspberry Pi Forum

Hi,

We are testing some sensors and have some strange values.

Sensors 4-20mA
wiring correct and bridge made.
Values comming in. INT 11500
all green leds on AIO

The values are just to much off to be correct. Not much.
So I was checking in piCtory if everything was fine. And that looks like ok.

The strange thing is (I think) that the value (INT) does not change (nor after reboot) if we change the range from 4-20mA to 0-20mA or 0-24mA.
Shouldnt the INT value be changing here a bit?

kind regards

Bryan

HI,
no it should not change if the current is the same. The value in the process image is the current measured in µA. So if you see a value of 11500 that means you are measurung 11,5 mA.
The range in PiCtory does only control the under/over current fault indication btu does have no influence on the physical unit of measurement: it is always a value in µA.
If you need any kind of transformation into other physical units (like preasure value in psi) then you need to adjust the offset and multiplicator/divisor parameters in PiCtory (see tutorials).
If you doubt the current value cou could simply install a multimeter in current measurement mode in series to the sensor and the AIO input.

Hi Volker,

We got it setup correctly. Our other hardware always uses the full INT range. Thats why we thought the INT should be moving.

4000 - 2000 INT is more logic.

thx