1. Basic Program Design Examples Control Program: M1002 Y1 The green lights will be ON and the red lights will be OFF when the program is started SET Y2 X1 M1 will be ON for one scan cycle when a car from the ground floor passes X1 . M2 will be ON for one scan cycle when a car from the basement passes X1 . M20=ON during the process of a car entering the passage from the ground floor . X2 M3 will be ON for one scan cycle when a car from the basement passes 2. X M4 will be ON for one scan cycle when a car from the ground floor passes 2. X M 0=O 3 N during the process of a car entering the passage from the basement.
M1 When a car runs in the passage, the red lights will be ON and green lights will be OFF. M4 M20 M2 When a car leaves the passage, the red lights will be OFF and green lights will be ON. M4 M20 M2 When a car leaves the passage, M20 and M30 will be reseted. Program Description: z The ground floor and the basement share the same red light signal Y1 and green light signal Y2. z The key of the program is to identify that the car is entering or leaving the passage at the ground floor entry/exit when M1 is ON to activate Y1 because [PLS M1] will be executed in both entering and leaving conditions.
Therefore, the confirming signal M20 is required for confirming that the car is entering the passage from the ground floor. z Also, it needs to identify that the car is entering or leaving the passage at the basement entry/exit when M3 is ON because [PLS M3] will be executed in both entering and leaving conditions. Therefore, the confirming signal M30 is required for confirming that the car is entering the passage from the basement. DVP-PLC Application Examples 1-17 RST PLS PLF M2 SET M20 PLS M3 PLF M4 SET M30 SET Y1 3 M20 RST Y2 SET Y1 RST Y2 RST Y1 0 SET Y2 0 RST M20 0 RST M30