The pulses output by the S7-1200 CPU are evaluated in the servo drive independently of the S7-1200 CPU. Internally, the S7-1200 CPU uses a high- speed counter which counts the number of output pulses, but it doesn’t receive feedback information on the actual position of the servo drive. The servo drive used in this example identifies the current position with the help of an encoder with four-fold evaluation. A motor with 2500 pulses per revolution generates 10000 pulses. To synchronize the pulses from the controller with the pulse counter of the drive, the drive end generates 4 pulses from each control pulse. In addition, the maximum frequency of the S7-1200 CPU has to be adjusted to the rated speed of the servo motor (see chapter 2.5). The servo drive then controls the motion of the servo motor. This procedure is illustrated in Figure 2-9.