Structure design of PLC control system

Linear programming Division of programming and structured programming (industrial mixing system).
Objects that are mixing requirements are as follows:

1. When component a (b) pump when required: 1) components of a (b) inlet valve has been opened, discharging valve is open; 2) mixing bucket is not full, the mixing valve closed; 3) the pump drive motor failure, do not have an emergency stop.
2. Mixing motor working conditions: 1) the mixing tank is not empty, mixing tank discharge valve closed 2) stirring motor failure, emergency stop without action.
3. Open discharge valve condition: mixing motor stop, emergency stop without action.
System of liquid level switch allows the operator understand the level of mixing drum, and provide linkage between pump and motor.

A linear programming
Linear programming is placed in a row within a block of instructions by the user program, that is, a simple block that contains all instructions of the system. Linear programming with no branches, usually OB1 sequentially each instruction, software management capabilities are relatively simple.

Second, partial program
Distributed programming tasks into a control several separate blocks, each block is used to control a device, or a set of logical instructions, these instructions within the block run by organizing block OB called.

Third, structured programming
Structure of program procedure requires the classification of similar or related functions, and tried to provide a universal solution can be used for several tasks. Provide relevant information to the instruction block (as a parameter), structured programs can reuse these common modules.

Control software consists of five functional blocks:
FC10 function block is used to control the ingredients a feed pump;
FC20 function blocks for controlling composition b material supply pump;
FC30 function block is used to control the mixing motor;
FC40 function block is used to control discharge solenoid valve;
FC50 function blocks for the LEDs on the control station.