I am not an electronics wiz and am stumped why analog input signals follow each other on my U6 set-up: Keyence IL1000 distance scanner (-5 to +5 VDC output analog signal with 100 ohm impendence) is connected to AIN0 on U6. The reference GND from the IL1000 is connected to GND on U6 with 100 ohm resistor in sseries. A 24VDC output from a small stepper motor is connected to AIN1 with a 22K resistor in series to pull the voltage down to 10VDC. The U6 is isolated and both analog inputs are powered externally. The IL1000 signal and REF GND wire to the U6 is shielded twisted pair. The motor signal uses a separate shielded cable. Both the IL1000 and stepper motor are powered from the same external DC power supply.
Using LJStreamUD, the data from AIN0 (distance scanner) looks good. However, the other analog channels follow AIN0 each with a small offset. AIN1 from the motor likewise follows AIN0 when low, but does properly go to 10V when high.
Connecting the external power supply ground directly to U6 ground flattens the signal on AIN0 to almost nothing; i.e. the proper data on AIN0 is only shown correctly when the IL1000 reference ground is connected to U6 GND.
During streaming using LJStreamUD, a laptop PC is connected to the U6 via USB with the PC running only on battery with it's power supply disconnected.
We do not have a real electronics guru on staff but are truely at a loss to our problem. I've tried 10K resistors between AIN0 and GND and AIN1 and GND which helps flatten the signals but does not correct the following problem.