STV is Zero Speed Command and RS is General Lock. Both signals are necessary for the servos.
But I also just see, my question was false. I want to switch signal 19 over the Mesa and ENA. With the old Sinumerik signal 10 (on both amplifiers) is switched with a safety relay and signal 19 (as far as I can see) is switched separately. The 15V is auxiliary voltage from the amplifier. I've already measured this. Therefore I think I can connect 19 to ENAx+ and 14 to ENAx-.
Marc
