Thaks Simon,
I was hoping that lack of galvanic isolation would help me in this case (so the current can complete a circuit through:
VOut0 --- +valve --- valve coil --- -valve --- VOut1 --- internal generator --- 0V (AOut1) ---lack of galvanic isolation --- OV (Aout0) --- Internal generator --- VOut0)
But since I'm completely unaware of hardware implementation of these internal generators, and PLCs altogether, I will not question your judgement
Since I'm over my budget with this project I'm going to aim at the cheap, safe solution which sould be analogue isolator that you mentioned as an option.
Thank you again!