Motor se detiene sin alguna instruccion MOTCON
How did you check SO1 is 0 ? , can you see that in Online builder in GEPCD command ?
According to your picture, MOTCON can be switched off if its inputs M2 or ACK1 are reset, even for a short time.
If you saw DO signal=0 but GEPCD live monitor showed MOTCON:SO1=1 then it is likely there is another logic that overwrites DO command.