1747-L552 The lift needs to go down, as long as there is a command to select the elevator, the downward direction relay is energised and its normally open point is closed, the latching relay is reset, Tim10 and Tim11 are de-energised, and its normally closed point is closed to prepare the lift for normal downward movement. The protection principle of the lower end station is similar to that of the upper end station and will not be repeated. Floor counting adopts relative counting method. Before the operation, through the self-learning method, it measures the number of pulses of the height of the corresponding floors, which are deposited into 16 memory units DM06 to DM21 corresponding to the 17 floors of the lift.

The 1747-L552 floor counter (CNT46) is a bi-directional counter, which counts plus 1 or minus 1 according to the running direction when it reaches the floor counting point of each floor. During operation, the accumulated value of the high-speed counter is compared in real time with the number of pulses corresponding to the floor counting points, and when equal, a floor counting signal is issued to add 1 to the upward line and subtract 1 to the downward line. to prevent the counter from repeating counting during the high level of counting pulses, the floor counter is triggered by the upper edge of the floor counting signal.

When the value of 1747-L552 high-speed counter is equal to the number of pulses corresponding to the fast speed change point, if the lift is in fast operation and there is a floor selection signal on the floor, a fast speed change signal will be issued. If the lift is in medium speed operation or there is no floor selection signal for this floor though it is in fast operation, no speed change signal will be issued. Door zone signal; when the value of high-speed counter CNT47 is within the range of the corresponding pulse number of door zone, the door zone signal is issued.