so that by the corresponding and element 108 or 109 further passage of the clock pulses from the pulse generator is suppressed for backward sewing for example for making a bar at the end of a seam switch 120 is actuated whereby at the beginning of a new pulse from the pulse generator 101 via the control lines 118a and 119a at the power stages 118 and 119 the control unit 105 reverses the direction of movement of the step motors 42 and 96 so that they drive the sliding wheel 47 and the roll foot 80 in reverse direction as long as the actuation of switch 120 lasts the execution of the step sequence of the step motors 42 and 96 occurs by calling the respective values set in the key panel 114 out of the data memory 116 in the manner described above during the stopping process of the sewing machine which usually ends in the upper dead center of needle 13 the control unit 105 switches the reversing arrangment 106 to input e1 so that the pulses delivered by oscilator 123 are applied to the inputs e1 of the and elements 108 and 109 as soon as the sewing machine stops clock pulses from oscillator 123 are thus placed on the inputs e1 of the.