AIO Input Values change when using other ports

HYPERH2 · Post by **HYPERH2** » 10 Jul 2019, 23:52

Currently I am using 7 ports on the AIO (28,27,23,6,5,2, and 1) which correspond to Inputs and Outputs 1 and 2. The AIO is plugged into the Connect. I am trying to read output voltages from a mass flow meter and a pressure transducer simultaneously. I am supplying 10 V to both devices, but the input range for the pressure transducer is 0-5 V whereas the mass flow meter is 0-10 V. Plugged in separately, they produce the correct values (measured and verified by a multimeter). However, when plugged in at the same time, the voltage values from the pressure transducer (InputValue_1) go way higher. The actual voltage measured from the transducer with a multimeter do not change. The mass flow meter does not seem to have this issue.
I have tried using different the input/output terminals and a different AIO, but the problem persists.
Any help is appreciated!

Post by **Eduard** » 11 Jul 2019, 10:54

Hi

According to the pinout of the RevPi AIO you have to use pins 28,26,24 for IN1 and 7,5,3,1 for OUT1.

HYPERH2 · Post by **HYPERH2** » 17 Jul 2019, 22:07

I am aware of the AIO pinout. The issue is that plugging two different devices into the AIO creates bleedover. I am using Inputs 1 and 2, and Outputs 1 and 2. The cables are correctly plugged in. Another issue I have is that when I gas through the mass flow meter, the Input LED blinks red. I'm thinking of using two separate AIOs for each device. Also, I find that sometimes when I remove the flow, I expect the byte value on-screen to go to zero, but it goes to 65535 instead. Any help to solve these issues is much appreciated.

Post by **Eduard** » 08 Aug 2019, 13:46

You still have to configure the input with the mass flow meter.
Please set the InputxOffset in piCtory to 1, after that the LED should not blink red anymore.
And after removing the mass flow meter you will be able to read a zero and no longer the value 65535.