What Is A Plc Programmer? Learn Basic Plc Programming

By Author: MC&TT CO., Ltd
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What is a PLC programmer?

PLC (Programmable Logic Controller), which is a programmable control device. Users can easily flexibly implement logic control algorithms through a programming language.

Before the PLC was born, to control an object (technology, line, machine operation...), engineers had to use a control relay circuit.

What about a relay controller? It's okay, as long as you can control the device? But there are many disadvantages when using a Relay controller, which are: bulky (takes up a lot of installation space), difficult to upgrade, expand, maintain, and repair.

Currently there are many PLC manufacturers such as: Cimon (Korea), Kinco (China), Siemens (Germany), Omron (Japan), Mitsubishi (Japan), Delta (Taiwan) ...

PLC programming languages include: LD (Ladder Logic), FBD (Function Block Diagram), STL (Statement List), SFC (Sequential Function Chart) in which Ladder Logic is the most popular PLC programming language.

Operating principle of PLC

The CPU receives signals from peripheral devices (such as sensors, switches, buttons...) through the input module. The signals ...
... will be processed by the CPU, executed according to the order of each command in the program, the control signals will be output through the output module to external control devices (such as contacters, motors, control valves...)

Scan Cycle – scan cycle includes reading the input signal, executing the program, internal communication, self-checking for errors, sending output signal updates. Usually, the execution of a scan cycle happens in a very short time (from 1ms-100ms). The time to execute this scan depends on the PLC's command processing speed, the length of the program, and the communication speed between the PLC and peripheral devices.

Today, PLC are widely used in all fields of electrical automation, serving many industries and types of machines such as water supply, wastewater treatment, energy monitoring, and monitoring. electrical systems, packaging machines, food processing machines, conveyor lines...etc

Advantages of PLC

- Rich documentation, many programming languages for users to choose from.
- Easily change and reprogram the program as desired.
- Large memory capacity, can perform complex algorithms with high accuracy.
- Compact and lightweight, easy to store and repair.
- Modular structure, allowing easy replacement, input/output expansion, and other function expansion.
- Can communicate with other smart devices such as: Computers, connect to communication networks with other devices.
= Good anti-interference ability, durable and continuous operation in industrial environments.
- Prices are increasingly competitive.

Basic PLC programming steps

Step 1: Carefully understand the object that needs to be controlled (such as technology, how it works...)

In the first step of the basic PLC programming process, the programmer needs to carefully understand the technological requirements to make programming easier.

Step 2: List

List all input/output modules, necessary modules for the system, etc. and select the PLC with the number of inputs and outputs greater or equal to the problem requirements.

Step 3: Assign PLC ports

Assign input and output ports to the PLC to facilitate programming, including:
Assign input and output ports according to required functions.
The entrance and exit ports are purposeful

Step 4: Build a program flow chart

Step 5: Convert flowchart to schema

Step 6: Based on the diagram, write a PLC program depending on the programming language you know best

Step 7: Test the program, run the simulation

View output results on PLC and on simulation software. Compare the problem with theory to see if it is correct.

Step 8: Connect the PLC programmer to the field device

Step 9: Check connection

Must check whether the connection pins are correct according to the principle diagram... to ensure that no unfortunate incidents occur.

Step 10: Run system check

Step 11: Accept and hand over and store the program

Source (Vietnamese Article): https://mctt.vn/bo-lap-trinh-plc-la-gi

The Measurement and Control Equipment Co., Ltd (MC&TT Co.,Ltd) established in March 2009 specializes in providing comprehensive and optimal Equipment - Solutions - Technical services in the field of Measurement - Control – Industrial Automation and Monitoring system. Aiming to build a credible and qualitative company, we have been becoming a leading company that supplies technical equipment and system integration services in Vietnam.