LED Par can
LED PAR LIGHT Series
54X3W rgbw; 18x12w RGBW;24x12w RGBW is hot selling in the market. It have waterproof and non-waterproof
Features:
suitable for events where indoor/outdoor flexibility is needed
Our company have 13 years experience of LED Display and Stage Lights , our company mainly produce Indoor Rental LED Display, Outdoor Rental LED Display, Transparent LED Display,Indoor Fixed Indoor LED Display, Outdoor Fixed LED Display, Poster LED Display , Dance Led Display... In additional, we also produce stage lights, such as beam lights Series, moving head lights Series, LED Par Light Series and son on...
LED Par Light Series,Led Par Can Lights,Par Can,Led Par Stage Light Guangzhou Chengwen Photoelectric Technology co.,ltd , https://www.cwleddisplay.com
**What is PLC Programming?**
PLC, or Programmable Logic Controller, is a fundamental control method widely used in industrial automation. It can be implemented through small-scale devices or large-scale systems and can interact with human-machine interfaces (HMIs) as well as communicate with computers. Originally designed to replace relay control circuits, PLCs have evolved into multi-functional, integrated controllers. The basic functions such as timers, counters, analog inputs, and outputs are all handled by the CPU unit of the PLC. In simple terms, a PLC acts like a microcontroller used for electrical control systems.
**Working Principle**
The PLC operates using a "sequential scanning, continuous cycling" approach. When running, the CPU reads the program stored in user memory according to the control requirements and performs periodic cyclic scans based on the instruction step number or address. If there is no jump instruction, it starts from the first instruction, executing them one by one until the end of the program, then returns to the beginning for the next cycle. During each scan, input signals are sampled, and output states are updated.
A complete scan cycle consists of three stages: input sampling, program execution, and output refresh. During the input sampling phase, the system reads the status of all input terminals and stores them in the input status registers. Then, the input ports are closed, and the program execution phase begins. In this phase, instructions are executed in the order they are stored in the user program. After processing, the results are written to the output status register.
In the output refresh phase, the state of the output status register is sent to the output latch, which then drives the corresponding output devices (such as relays, transistors, or other actuators). This ensures that the physical outputs reflect the current state of the program.
**Characteristics**
PLC programming is versatile, powerful, and user-friendly, making it a key component of modern industrial automation. It has found widespread use across various industries, including manufacturing, civil engineering, and home automation. The IEC (International Electrotechnical Commission) defines a PLC as an electronic system designed for industrial environments, capable of performing logic operations, sequence control, timing, counting, and arithmetic operations through programmable memory. It is also designed to easily integrate into larger control systems and expand its functionality.
The application of PLC programming has grown rapidly in China, especially in mechanical equipment and electrical control systems. Understanding the working principle of PLCs and having the ability to design, debug, and maintain PLC-based control systems has become a fundamental requirement for electrical engineers and students in the field.
**PLC Programming and Application Practice**
With so many PLC programming software options available, it's not feasible to cover them all. Therefore, this article uses the popular Siemens STEP 7-Micro/WIN programming software as an example to demonstrate how to write a PLC control program.
**1. Fountain Control**
1) Define System Control Requirements
The system requires two buttons to control three groups of nozzles (A, B, and C), each driven by a pump motor. The nozzles are arranged as shown in the diagram below.
[Image: Fountain Nozzle Arrangement]
The control sequence is as follows:
- Pressing the start button triggers A group nozzles to spray for 5 seconds, then stop.
- B and C groups spray simultaneously for 5 seconds, after which B stops and C continues for another 5 seconds.
- Then A and B spray for 7 seconds, with C stopping after 2 seconds.
- All nozzles stop for 3 seconds before repeating the cycle.
- Pressing the stop button halts all nozzles immediately.
[Image: Fountain Nozzle Working Sequence]
2) Identify Input/Output Devices and Assign I/O Terminals
The input/output devices and their corresponding PLC terminals are listed in the table below.
[Table: Input/Output Assignment for Fountain Control]
3) Draw the Fountain Control Circuit Diagram
[Image: Fountain Control Circuit Diagram]
4) Write the PLC Control Program
Using the STEP 7-Micro/WIN software, a ladder logic program is created to meet the control requirements.
[Image: Ladder Diagram for Fountain Control]
The working principle of the ladder diagram is explained in detail, showing how the start and stop controls function.
**2. Traffic Signal Control**
1) Define System Control Requirements
This system uses two buttons to control traffic lights arranged as shown.
[Image: Traffic Light Arrangement]
The control sequence is as follows:
- Pressing the start button turns on the north-south red lights for 25 seconds.
- East-west green lights turn on for 20 seconds, then flash 3 times at 1 Hz.
- East-west yellow lights stay on for 2 seconds.
- North-south red lights turn off, and green lights come on for 25 seconds, flashing 3 times at 1 Hz.
- Yellow lights remain on for 2 seconds.
- The cycle repeats.
- Pressing the stop button turns off all lights.
[Image: Traffic Light Timing Diagram]
2) Identify Input/Output Devices and Assign I/O Terminals
[Table: Input/Output Assignment for Traffic Signal Control]
3) Draw the Traffic Signal Control Circuit Diagram
[Image: Traffic Signal Control Circuit Diagram]
4) Write the PLC Control Program
Using the same STEP 7-Micro/WIN software, a ladder diagram is created.
[Image: Ladder Diagram for Traffic Signal Control]
The ladder diagram includes the use of SM0.5, a special auxiliary relay that generates a 1-second clock pulse. This allows for accurate timing and flashing of lights, as demonstrated in the diagram.
[Image: Start and Stop Control Networks]
By following these steps, students and engineers can gain practical experience in designing and implementing PLC-based control systems.