Rockwell Automation 9323-S5500D A.I. SERIES MICROLOGIX 1000 AND PLC-500 SOFTW - Manual (Page 381)

Channel Configuration
16-3
3. Use the arrow keys to move the highlight to the System Mode Driver field for the
channel you want to disable or enable. (For CH0, make sure that the Current
Communication Mode is set to System .)
4. Press [F9] Select until Shutdown appears in the field.
5. Press [F1] Accept to accept the change.