Cable Tension Monitor

A movable barrier system comprising:

• a movable barrier operator configured to move a movable barrier in a first direction and a second direction;
• an elongate member capable of being connected to the movable barrier;
• a rotatable drum rotatable about an axis and having an external surface configured to receive the elongate member thereon, the external surface extending about the rotatable axis and having a predetermined width along the axis;
• the elongate member configured to wind up on and pay out from the external surface of the rotatable drum to at least support corresponding movement of the movable barrier;
• and
• a sensor apparatus comprising a sensing portion configured to extend across the external surface of the rotatable drum, the sensing portion configured to sense a proximity of the elongate member relative to the sensing portion at a plurality of sensing regions along a central longitudinal axis of the sensing portion, wherein the sensing portion is shapeable to complement the external surface of the rotatable drum so that the sensing portion has a generally constant distance from the external surface of the rotatable drum;
• and
• a controller connected to the sensing portion, the controller configured to receive information from the sensing portion to detect a change in the proximity of the elongate member relative to any of the sensing regions along the width of the external surface of the rotatable member without the elongate member contacting the sensing portion,
• wherein the controller is further configured to effect, by the movable barrier operator, at least one of a stoppage of rotation of the rotatable drum and a reversal of rotational direction of the rotatable drum in response to the change in the proximity of the elongate member relative to the sensing portion according to the information received from the sensing portion.

A method comprising:

• sensing, by a sensor, a first spaced apart proximity of an elongate member connected to a rotatable drum relative to a shapeable sensing portion of the sensor, the shapeable sensing portion shaped to complement an external surface of the rotatable drum such that the shapeable sensing portion has a generally constant distance from the external surface of the rotatable drum;
• sensing, by the sensor, a second spaced apart proximity of the elongate member relative to the shapeable sensing portion, the second spaced apart proximity different than the first spaced apart proximity;
• in response to sensing the second spaced apart proximity different than the first spaced apart proximity, determining a change in proximity of the elongate member relative to the shapeable sensing portion of the sensor;
• transmitting a signal to effect at least one of a stoppage of the rotatable drum and a reversal of rotational direction of the rotatable drum in response to determining the change in proximity of the elongate member relative to the shapeable sensing portion.