This simple circuit from a 1987 documentation can be used in robotics and automation, as well as being controlled by microcontrollers such as Power Shield. The relay is 5 to 12 V depending on the type of control and for best performance 1k resistors must be connected in series with the bases of the transistors. The control functions are:
E1 E2 Function
0 0 stopped
0 1 inverse
1 0 stopped
1 1 direct