Thanks sergiucip for good howto.
A small additional:
chmod +x /npc/npc
needed for new script file

I also start ftp server and try to send output to file:

#!/bin/sh
telnetd &
tcpsvd -vE 0.0.0.0 21 ftpd -w /mnt &
mount /dev/mmcblk0p1 /mnt/disc1 -t vfat -o relatime
/npc/npc-exe &>/mnt/disc1/npc ...