What are the characteristics of ladder diagrams?

(2) The left and right busbars in the relay control circuit diagram are power lines, and voltages are applied to the middle branches. When the branches are connected, current flows through the contacts and coils on the branch.

(3) The various devices (ie, devices) used in the ladder diagram are referred to by the corresponding names in the relay control circuit diagram, and are not real physical devices (ie, hardware relays).

(4) The state of the input relay in the ladder diagram depends solely on the on/off state of the corresponding input signal, regardless of the execution of the program.Therefore, the input relay in the ladder diagram cannot be driven by the program, that is, the coil of the input relay cannot appear.

(6) The contacts of each device in the ladder diagram have both dynamic and dynamic breaks, and the number of moving and breaking contacts is infinite (and will not be damaged). How much is required for ladder programming?How much is used, but the hard contacts of the input and output relays are limited and need to be properly allocated.The logic operation is based on the state in the component image register, not on the state of the external input signal at the instant of the operation.