How can you use structured text in PLC programming for different industries?

3 How to use structured text for automotive industry?

One of the advantages of ST is that it can handle complex mathematical and logical operations that are often required in the automotive industry. For example, you can use ST to calculate the speed, torque, and position of a servo motor that controls a robotic arm for welding or assembly. You can also use ST to implement state machines, timers, counters, and loops that can control the sequence and timing of different processes and actions. Here is an example of a ST program that uses a state machine to control the movement of a robotic arm:

PROGRAM RoboticArm
VAR
  State : INT; //variable for state machine
  Speed : REAL; //variable for speed calculation
  Torque : REAL; //variable for torque calculation
  Position : REAL; //variable for position calculation
  Command : INT; //input variable for command
  Servo : BOOL; //output variable for servo
END_VAR
//program body
CASE State OF
  0: //initial state
    IF Command = 1 THEN //if command is 1, go to state 1
      State := 1;
    END_IF
  1: //state 1
    Speed := 10.0; //set speed to 10.0
    Torque := 5.0; //set torque to 5.0
    Position := 0.0; //set position to 0.0
    Servo := TRUE; //turn on servo
    State := 2; //go to state 2
  2: //state 2
    Position := Position + Speed * 0.1; //calculate position
    IF Position >= 90.0 THEN //if position is 90.0 or more, go to state 3
      State := 3;
    END_IF
  3: //state 3
    Speed := 0.0; //set speed to 0.0
    Torque := 0.0; //set torque to 0.0
    Servo := FALSE; //turn off servo
    State := 0; //go back to initial state
END_CASE
END_PROGRAM        

4 How to use structured text for food and beverage industry?

Another benefit of ST is that it can handle data manipulation and communication that are often needed in the food and beverage industry. For example, you can use ST to read and write data from sensors, actuators, and other devices that monitor and control the temperature, pressure, level, flow, and quality of the products. You can also use ST to communicate with other PLCs, human-machine interfaces (HMIs), databases, and networks that store and exchange information and commands. Here is an example of a ST program that reads the temperature of a tank from a sensor and displays it on an HMI:

PROGRAM TankTemperature
VAR
  Temp : REAL; //variable for temperature
  Sensor : REAL; //input variable for sensor
  HMI : REAL; //output variable for HMI
END_VAR
//program body
Temp := Sensor * 0.1; //convert sensor value to temperature
HMI := Temp; //send temperature value to HMI
END_PROGRAM        

5 How to use structured text for pharmaceutical industry?

A third advantage of ST is that it can handle safety and security features that are often required in the pharmaceutical industry. For example, you can use ST to implement interlocks, alarms, and emergency stops that can prevent or stop hazardous situations and protect the workers and the equipment. You can also use ST to encrypt and decrypt data and messages that can ensure the confidentiality and integrity of the records and the transactions. Here is an example of a ST program that uses an interlock to prevent a pump from running if the pressure is too high:

PROGRAM PumpInterlock
VAR
  Pump : BOOL; //output variable for pump
  Pressure : REAL; //input variable for pressure
  HighLimit : REAL; //constant variable for high limit
END_VAR
//program body
HighLimit := 100.0; //set high limit to 100.0
IF Pressure > HighLimit THEN //if pressure is higher than high limit, turn off pump
  Pump := FALSE;
ELSE //if pressure is lower than or equal to high limit, turn on pump
  Pump := TRUE;
END_IF
END_PROGRAM