Abstract: Pulses produced by a pulse generator coupled to the output shaft of an electric motor that reciprocates a polish rod of a well pumping system are counted by a computer to locate the polish rod at a series of positions during each reciprocation of the polish rod and the dynamic load on the polish rod at each of these positions is determined by the computer from the time difference between pulses. The pulse count and dynamic loads are simultaneously displayed on a two-dimensional array of light emitting diodes under the control of the computer to visually present the dynamic pumping characteristics of the system. The operation of the system following pump off or breakage of a sucker rod is interrupted by controlling the operation of the motor via the computer, the computer switching off the motor following the occurrence of a preselected set of dynamic loads for a preselected set of pulses.