Abstract: A control system for longwall mining roof supports which are controlled in dependence on the position of the mining machine at any time. All of the roof supports are connected to a central computer via common conductors. Each of the roof supports includes a control unit having a code corresponding to the number of that support. This code serves as an address and enables the central computer to transmit its control command signals positively, in response to the mining machine position signals, through an appropriate address control unit for a particular roof support. In order to enable roof supports to be actuated manually also, the control units of all of the roof supports are connected to the central computer by two common conductors, one of which carries an automatic enable signal and the other of which carries a manual enable signal.