Abstract: A control unit includes a power supply board on which a control power-supply circuit that generates a control voltage is mounted, a control board on which a control circuit that is operated based on the control voltage is mounted, and a connection medium that connects the power supply board and the control board to each other and is used to supply the control voltage from the control power-supply circuit to the control circuit. A signal ground of the control power-supply circuit and a signal ground of the control circuit are connected to each other via a frame ground without via the connection medium.

Abstract: A control unit includes a power supply board on which a control power-supply circuit that generates a control voltage is mounted, a control board on which a control circuit that is operated based on the control voltage is mounted, and a connection medium that connects the power supply board and the control board to each other and is used to supply the control voltage from the control power-supply circuit to the control circuit. A signal ground of the control power-supply circuit and a signal ground of the control circuit are connected to each other via a frame ground without via the connection medium.

Abstract: A control system includes: a control device that controls operations of a drive device; and a connecting line that connects the control device and the drive device. The control device includes: a ready-on unit configured to output a ready-on signal that permits the drive device to operate; a safety device configured to control output of the ready-on signal based on the ready-on signal input from the ready-on unit and a connection state of the connecting line; and a control unit configured to supply power to the drive device and to control operations of the drive device based on a ready-on signal input from the safety device. The connecting line includes an attachment/detachment determination line that outputs a signal input from the safety device to the safety device in return.