The servo amplifier shows error F04 (feedback loss) in mode electronic gearing via X1. The wiring is corrects, what's wrong?

By default, S300 and S700 check  the X1 sense lines (feedback voltage supply). In Master-Slave or Electr.Gearing operation no supply voltage is required and the sense lines are not connected.

Solution: Bit 20 of parameter DRVCNFG2 of the servo amplifier disables the supervision of the sense lines (DRVCNFG2=DRVCNFG2+1048576).