1. Motor Control Case
5. Electric Motor Y-△ Reduced Voltage Start
Control Requirements
The electric motor should first start with a Y connection for reduced voltage, and after a delay, switch to a △ connection for full voltage operation.
Main Instructions Used
LD, OR, ANI, OUT, TMR
Control Logic
· At startup, the main contactor and the Y contactor are energized.
· The timer counts (usually 5-10 seconds).
· When the timer expires, the Y contactor opens, and the △ contactor closes.
· A brief delay is added during the Y-△ switch to prevent short-circuiting.
Program Example
LD X0 // Start Button
OR M0
ANI X1 // Stop Button
OUT M0
LD M0
OUT Y0 // Main Contactor
OUT Y1 // Y Contactor
OUT T0 K100 // Timer10 seconds
LD T0
OUT Y2 // △ Contactor
ANI Y1 // Interlock, ensure Y is off
6. Sequential Start of Multiple Motors/Reverse Order Stop
Control Requirements
Multiple electric motors should start sequentially and stop in reverse order.
Main Instructions Used
LD, OR, ANI, AND, OUT
Control Logic
· After the previous motor starts, its normally open contact serves as the condition for starting the next motor.
· Use a timer to achieve staggered starting.
· Reverse order stop: The normally open contact of the last motor serves as the condition for stopping the previous motor.
· An emergency stop button can stop all motors simultaneously.
Program Example
// M1 Start
LD X0 // Start Button
OR Y0
ANI X1 // Stop Button
OUT Y0 // M1 Running
// M2 Start after M1 delayed start
LD Y0
OUT T0 K50 // Delay5 seconds
LD T0
OR Y1
ANI X1
ANI Y2 // M3 cannot stop M2 while running
OUT Y1 // M2 Running
// M3 Start after M2 delayed start
LD Y1
OUT T1 K50 // Delay5 seconds
LD T1
OR Y2
ANI X1
OUT Y2 // M3 Running
2. Comprehensive Application Cases
7. Traffic Light Control System
Control Requirements
Implement automatic cyclic control of traffic lights at an intersection.
Main Instructions Used
LD, OUT, ANI, OR, TMR
Control Logic
· The north-south red light is on for 25 seconds, while the east-west green light is on for 20 seconds, followed by a flashing light for 3 seconds, and a yellow light for 2 seconds.
· The east-west red light is on for 30 seconds, while the north-south green light is on for 25 seconds, followed by a flashing light for 3 seconds, and a yellow light for 2 seconds.
· Use multiple timers to achieve control for each time period.
· Use special relay M8013 to achieve the flashing effect of the green light.
Program Structure Example
// North-South Control
LD X0 // Start Switch
OUT T0 K250 // North-South Red Light25 seconds
OUT T1 K200 // East-West Green Light20 seconds
OUT T2 K230 // East-West Green Light Flashing Starts
OUT T3 K250 // East-West Yellow Light Starts
// … More timer controls
// Output Control Logic
LD T0
ANI T4
OUT Y0 // North-South Red Light
LD T4
ANI T5
OUT Y1 // North-South Green Light
LD T5
ANI T6
AND M8013 // 1 second clock pulse
OUT Y1 // North-South Green Light Flashing
// … More output controls
8. Liquid Mixing Device Control
Control Requirements
Control two types of liquids to mix in proportion, stir, and then discharge.
Main Instructions Used
LD, AND, OR, OUT, TMR
Control Logic
· Press the start button to open the A liquid valve.
· When the liquid level reaches L2, close the A valve and open the B valve.
· When the liquid level reaches L1, close the B valve and start the stirring motor.
· Stir for 10 seconds, then stop and open the discharge valve.
· When the liquid level drops below L3, delay for 5 seconds before closing the discharge valve to complete a cycle.
Program Structure Example
// Start Control
LD X0 // Start Button
OR M0
ANI X1 // Stop Button
OUT M0
// A Liquid Injection
LD M0
ANI X3 // L2 Liquid Level Switch
OUT Y0 // A Liquid Valve
// B Liquid Injection
LD X3 // L2 Liquid Level Switch
ANI X2 // L1 Liquid Level Switch
OUT Y1 // B Liquid Valve
// Stirring Control
LD X2 // L1 Liquid Level Switch
OR M1
ANI T0 // Stirring Time Expired
OUT M1
OUT Y2 // Stirring Motor
OUT T0 K100 // Stir10 seconds
// Discharge Control
LD T0
OR M2
ANI X4 // L3 Liquid Level Switch
OUT M2
OUT Y3 // Discharge Valve
》》》》》》》》》Previous Reviews《《《《《《《《《1. Detailed Explanation of Interrupt Control in Mitsubishi PLC2. Detailed Explanation of Floating Point Applications in Mitsubishi PLC3. Mitsubishi FX Series PLC Achieving Constant Pressure Water Supply Closed Loop Control System via Analog Module4. Detailed Explanation of Data Types and Array Types in Mitsubishi FX Series PLC5. Detailed Explanation of CC-Link Communication Technology in Mitsubishi Q Series PLC6. Detailed Explanation of Controlling Inverters via RS485 RTU Communication with Mitsubishi FX3U7. Detailed Explanation of Modbus Communication Protocol8. Detailed Explanation of ST Language Instructions in Omron NJ Series PLC9. Omron NJ Series PLC Socket Communication Guide10. Omron NJ Series PLC Function Block (FB) Programming Guide》》》》》》》》》END《《《《《《《《《