For most of our simpler installations, we use 230 VAC for our hard-wired safety devices (as in independent from the PLC). This has been done for decades in our company, and one of the reasons was that in case of an defect of the cable or device, the fuse would trip, taking the safety relays with it.
That being said, we have never (as far as I know), wired these directly to the PLC. Always through relays.
That being said, we have never (as far as I know), wired these directly to the PLC. Always through relays.