Safety Rated Signals Over Profibus?

I'm on a job where the robots will be connected to a Seimens PLC via profibus. The controls guy is adamant that we can do all the safety over profibus (fence, estop, servo off, etc). In my experience with other safety comm protocols (profinet, ethernet/IP), this is accomplished by buying the appropriate safety comms from fanuc, then mapping the safety signals via DCS safe-io. However, I can find nothing in the DCS or profibus manuals regarding safety over profibus.

Has anyone here ever done safety rated signals over profibus? If you have, how was it accomplished?

Some updates: Finally got some cabinet pictures from another cell on site that the controls guy also stated was doing safeties over profibus, and lo and behold, all the safeties are hardwired.