a coupling device which removably couples the portable measurement device to {HEAD ~ a port} in the moveable barrier operator, the measuring circuit generating an impact force signal representing {TAIL ~ an impact force measurement} and effecting transmission of the impact force signal from the interface to the movable barrier operator 
a coupling device which removably couples the portable measurement device to { HEAD ~ a port } in the moveable barrier operator , the measuring circuit generating an impact force signal representing { TAIL ~ an impact force measurement } and effecting transmission of the impact force signal from the interface to the movable barrier operator
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