Abstract: The invention disclosed is useful in an I/O system of a programmable controller and provides a method and circuitry by which control and diagnostic information is exchanged between a control unit of an I/O module and a plurality of input/output points of the I/O module. A control signal is generated in the control unit in the form of sequential pulse frames such that the control information is defined by a series of pulse width modulated pulses. Each frame includes a no-pulse time period following the review of pulses to mark the end of a frame. Each I/O point receives a control signal of its own and generates a clock pulse in response to each pulse. The clock pulse initiates a sampling of the corresponding pulse and simultaneously initiates return of a diagnostic signal value to the central unit by implementation of firmware in a switch processor. Thus, the control signal provides for sampling of its own content and provides for a return of a diagnostic data bit for each control bit.

Abstract: A foldable root crop defoliator wherein the implement has a central frame with lateral wings pivotally attached to the central frame. The front end of the central frame is adjustably attached to a hitch for towing the defoliator. Plant top cutting and shredding devices are mounted to the wing frames and are driven by a power train connected to the power-take-off (PTO) of the towing vehicle. In a use orientation, the two lateral wings are independently adjustable relative to the ground. Also, they have a range of free motion, and are able to "float" independently over the ground that they are immediately above. For a travel or storage orientation, each lateral wing is rotated upward to a vertical position by actuating a lifting device mounted on the central frame. The lifting device includes, for example, a piston and cylinder, and toggle linkage assembly. By being foldable, the defoliator may be reduced to a much smaller width, making it safer to transport and easier to store.