The system may also include a contact closure interface having {HEAD ~ inputs} for connection of an alternate device or control system to {TAIL ~ the contact closure interface} for generating command signals for controlling one or more of the drive units 
The system may also include a contact closure interface having { HEAD ~ inputs } for connection of an alternate device or control system to { TAIL ~ the contact closure interface } for generating command signals for controlling one or more of the drive units
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH