... what are the requirements of EN 415-10 for a safety PLC?

Section 5.16.3 of DIN EN 415-10 describes under point h) the activities with open guards. The set-up mode with the guard open is therefore only permitted at reduced speed, reduced power, reduced pressure or reduced energy supply. A safety controller can be used to evaluate these parameters.

Section 5.14.7 also describes the stopping time. The safety controller of the machine must ensure that hazardous functions stop after opening a locked movable guard and that the safety distance is maintained

If this cannot be implemented, the standard prescribes the use of guards with guard locking. For further details and the requirements for a guard locking, please refer to DIN EN 14119:2003, Chapters 5.7, 5.2 and 5.3.