The IEC (International Electrotechnical Commission) announced the PLC standard (IEC1131) in May 1994. It consists of five parts: general information, equipment and test requirements, programming languages, user guides, and communications. The third part (IEC1131-3) is the programming language standard for PLC. IEC1131-3 details the syntax, grammar and expressions of the five programming languages ??of PLC.
The five programming languages ??of PLC are:
1. Sequential function chart: Sequential function chart is a graphical language located on top of other programming languages. It is mainly used to prepare sequential control programs. . The sequential function diagram provides a graphical direction for organizing the program and can be used to describe the functions of the system. According to it, the ladder diagram can be easily drawn.
#2. Ladder diagram: Ladder diagram is the most commonly used graphical programming language for PLC programming. As mentioned earlier, the ladder diagram is very similar to the circuit diagram of the traditional relay control system. It has the advantage of being intuitive and easy to understand. It can be easily mastered by electrical personnel familiar with the relay control system in the factory. It is especially suitable for switching logic control. Ladder diagrams consist of contacts, coils, and function blocks represented by boxes. Contacts represent logical input conditions, such as external switches, buttons, etc. Coils usually represent logical output results and are used to control external indicators, contactors, etc. Function blocks are used to represent timers, counters, or additional instructions for mathematical operations.
#3. Function module diagram: This is a programming language similar to digital logic gate circuits, and it is easy for people with a foundation in digital circuits to master. This programming language uses boxes similar to AND, OR, and NOT gates to represent logical operations. The left side of the box is the input variable of the logical operation, the right side is the output variable, and the signal flows from left to right.
#4. Instruction list: (Siemens calls it statement list) A program composed of several instructions is called an instruction list. The instruction of PLC is a mnemonic expression similar to the instruction in microcomputer assembly language, consisting of operation code and operand. The instruction system of a small PLC is much simpler than that of assembly language. Only about 20 instructions can control the switching value. However, the instruction list program is difficult to read, and the logical relationships are difficult to see at a glance. Therefore, ladder diagrams are generally used when designing more complex switching control programs. The instruction list can handle some problems that cannot be solved with ladder diagram.
5. Structured text: Structured text is a dedicated high-level programming language created by the IEC1131-3 standard, which can enhance PLC's mathematical operations, data processing, graphic display, Report printing and other functions. It can be said to be an advanced application of PLC, so it is mostly used by programmers who have received professional computer programming training.
Among the above five programming languages, the most commonly used ones are ladder diagram and instruction list (statement list). Beginners must master these two programming languages ??well. There is a certain correspondence between the ladder diagram and the instruction list, and they can be converted into each other. Siemens PLC programming software uses ladder diagram programming and statement list programming as the main interfaces. No matter what language the user writes the program, another program is required. If so, it will be converted automatically.
The above is the detailed content of What are the plc programming languages?. For more information, please follow other related articles on the PHP Chinese website!

Hot AI Tools

Undress AI Tool
Undress images for free

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Clothoff.io
AI clothes remover

Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

Hot Tools

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Chinese version
Chinese version, very easy to use

Zend Studio 13.0.1
Powerful PHP integrated development environment

Dreamweaver CS6
Visual web development tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

System restore point setting methods include manual creation, dependency automatic creation, and management of storage space. 1. Manual creation requires system protection to enable in "Create Restore Point", allocate 5% disk space and click "Create" to name the restore point; 2. The system will automatically create restore points when installing updates or changing settings, but do not guarantee comprehensiveness; 3. The restore point occupies no more than 5% of the system disk space by default, and the old version will be automatically cleaned, and storage can be managed by adjusting the upper limit.

If you want to remotely turn off the router Wi-Fi, you must first confirm whether the router supports remote management; if it does not support it, it can be achieved through a smart socket power outage; advanced users can also consider flashing in custom firmware. The specific steps are as follows: 1. Check whether the router has remote management functions, such as the manufacturer's supporting app or cloud management functions; 2. If it is not supported, purchase and set up a smart socket and remotely cut off power through its app; 3. For technical users, you can install firmware such as DD-WRT or OpenWRT to obtain remote control permissions. Different methods have their own advantages and disadvantages. Please weigh them according to your own needs when choosing.

A firewall is a network security system that monitors and controls network traffic through predefined rules to protect computers or networks from unauthorized access. Its core functions include: 1. Check the source, destination address, port and protocol of the data packet; 2. Determine whether to allow connections based on trust; 3. Block suspicious or malicious behavior; 4. Support different types such as packet filtering firewalls, status detection firewalls, application layer firewalls and next-generation firewalls; 5. Users can enable built-in firewalls through operating system settings, such as Windows Security Center or macOS system preferences; 6. The firewall should be used in combination with other security measures such as strong passwords and update software to enhance protection.

When encountering the blue screen error VIDEO_TDR_FAILURE(nvlddmkm.sys), priority should be given to troubleshooting graphics card driver or hardware problems. 1. Update or rollback the graphics card driver: automatically search and update through the device manager, manually install or roll back to the old stable driver using NVIDIA official website tools; 2. Adjust the TDR mechanism: Modify the TdrDelay value in the registry to extend the system waiting time; 3. Check the graphics card hardware status: monitor the temperature, power supply, interface connection and memory module; 4. Check system interference factors: run sfc/scannow to repair system files, uninstall conflicting software, and try safe mode startup to confirm the root cause of the problem. In most cases, the driver problem is first handled. If it occurs repeatedly, it needs to be further deepened.

To prevent specific programs from being connected to the network can be achieved through system firewalls or third-party tools. 1. Windows users can use their own firewall, create new rules in the "outbound rules" to select the program path and set "block connection"; 2. Third-party tools such as GlassWire or NetBalancer provide graphical interfaces that are more convenient to operate, but pay attention to source reliability and performance impact; 3. Mac users can control networking permissions through the command line with pfctl or using LittleSnitch and other tools; 4. A more thorough way is to use the network outage policy. The whitelisting policy prohibits all programs from being connected to the network by default and only allows trusted programs to access. Although the operation modes of different systems are different, the core logic is consistent, and attention should be paid to the details of the path and scope of the rules taking effect.

UAC frequently pops up because the running program requires administrator permissions or the system setting level is too high. Common reasons include installation of software, modifying system settings, running third-party tools and other operation triggers. If using an administrator account, UAC only confirms the operation and not blocks. The methods for reducing prompts include: canceling the program to run as an administrator, lowering the UAC notification level, using a standard user account, and starting the program through the task planner. It is not recommended to turn off UAC completely because it can effectively prevent malicious programs from tampering with the system. You can set the UAC to "notify only when the program changes the computer" to balance security and experience.

The Facebook name change process is simple, but you need to pay attention to the rules. First, log in to the application or web version and go to "Settings and Privacy" > "Settings" > "Personal Information" > "Name", enter a new name, and save it; secondly, you must use your real name, it cannot be modified frequently within 60 days, it cannot contain special characters or numbers, and it cannot be impersonated by others, and the review does not pass the auxiliary verification such as uploading ID cards; it usually takes effect within a few minutes to 3 working days after submission; finally, the name change will not notify friends, the homepage name will be updated simultaneously, and the old name will still be displayed in the history record.

Updating the wireless router firmware is necessary and easy to operate. 1. Updates can fix vulnerabilities, improve performance, and add functions; 2. Check and updates can be manually operated through the management interface; 3. During updates, you need to ensure stable power supply, use wired connections, avoid interruptions, and confirm model matching; 4. Some brands support automatic updates, and update once or twice a year.