Designing a PLC control system requires the following seven steps:
1. System Design and Equipment Selection
a . Analyze the equipment or system you control. The primary purpose of a PLC is to control external systems. This system could be a single machine, a group of machines, or a production process.
b . Determine whether the number of input/output points of the device or system you want to control meets the requirements of the programmable logic controller (PLC). (Selection Requirements)
c . Assess the complexity of the device or system you are trying to control and analyze whether the memory capacity is sufficient.
2. I/O assignment (assigning inputs and outputs)
a . Assign values to the input signals of the device or system you want to control, corresponding them to the input numbers of the PLC. (List)
b . Assign values to the output signals of the device or system you want to control, corresponding them to the output numbers of the PLC. (List)
3. Design the control principle diagram
a . Design a relatively complete control sketch.
b . Write your control program.
c . Simplify the procedure as much as possible while achieving your control objectives.
4. Write the program to the PLC
Write your program into the programmable controller.
5. Edit, debug, and modify your program.
a . Program debugging (logic and syntax checks)
b . Insert END in a local section and debug the program in segments.
c . Overall operation and debugging
6. Monitor operational status
In monitoring mode, check if each action of your control program is correct. If not, return to step 5; if correct, proceed to step 7.
7. Run the program (don't forget to back up your program!)
