There is an electric hoist in one workshop, which is used for unloading up and down, and the forward, backward, upward, and downward movements are controlled by the handle, as shown in Figure 1-1.
Figure 1-1: Electric hoist.
Its control requirements are:
1.Press the emergency stop button, the hoist cannot move;Emergency stop unscrewed out, you can operate the button;
2.Press the forward button, the front and rear motors of the hoist move forward, and when the front limit switch is reached, it can not move forward;
3.Press the backward button, the front and rear motors of the hoist are backward, and when the rear limit switch is reached, it can not be retreated;
4.Press the up button, the hoist lifting motor rises;When the upper limit switch is reached, it cannot be raised again;
5.Press the down button, and the hoist lift motor descends;There is no lower limit switch, and the descent limit is judged manually.
Figure 1-2 PLC control wiring diagram.
Figure 1-2 PLC control wiring diagram. 
Figure 1-3 Wiring diagram of the main circuit.
Figure 1-4 Control Flow Diagram.
Figure 1-5 S7-1200 Program Segment 1
Figure 1-6 S7-1200 Program Segment 2
Figure 1-7 S7-1200 Segment 3
Figure 1-8 S7-1200 Program Section 4
Figure 1-9 S7-1200 Program Section 5
In this case, the use of PLC to realize the case of electric hoist, this is just one of the implementations. When programming, the transfer of program steps is carried out by comparing and assigning values, which is also a common programming method, if you have more solutions and programming methods, please leave a message.