cpu 110 by a conventional data highway or bus utilizing allen bradley data communication protocol the outputs of the control panel 86 i e signals from a mode selector switch start and stop pushbuttons or other operator input are input to the plc 120 the plc 120 is response to various inputs executes a stored control program to activate various outputs as described hereafter further inputs to the plc 120 include signals 122 and 124 which are respectively output from the horizontal encoder 200 connected to the x axis drive motor 24 and the vertical encoder 198 connected to the y axis drive motor 44 any conventional encoder may be employed which generates a pulse for each predetermined amount of rotation of the motor output shaft to indicate the position of the movable member driven by the respective motors 24 and 44 the encoder outputs 122 and 124 are input to the plc 120 and used by the plc 120 when executing its control program to generate signals to x and y drivers 126 and 128 respectively connected to the x and y drive motors 24 and 44 by example only the x and y drivers 126 and 128 may be variable frequency drives such as a variable frequency drive model number 1305 sold by allen bradley also input to the plc 120 is an input signal labeled 34 body style 34 which may be.