The ASCII save command is as follows:
nhSaveDb -p $NH_HOME/db/save/daily.tdb -ascii -u $NH_USER
To create the ASCII save as a job than can be scheduled use the following command
nhSchedule -defineType "Ascii-DB-Save" -load 100 -cmd "nhSaveDb -p $NH_HOME/db/save/daily.tdb -ascii -u $NH_USER"
You may need to set the path and user instead of the variables included above.
Then you can schedule it as follows
nhSchedule -schedule "Ascii-DB-Save" -time "2:00 AM" -daily ûyyyyyyy