kenwood120s:
Is that at me or OP?- he's talking 9V and the 7-12V and 1A thing sounds like power to me, not provision of a PLC output to be conditioned down to an Arduino digital input which would of course be 5V.
OP.
Talking about a 24-9V converter, that's why it seems he wants to power the Arduino with the PLC's 24V.