There are 5 languages that are all a part of the IEC (International
Electrotechnical Commission) Section 61131-3 Standard. This IEC Standard
allows some ground rules that standardize PLC’s and their languages.
The 5 most popular PLC programming languages are Ladder Diagram (LD),
Sequential Function Charts (SFC), Function Block Diagram (FBD),
Structured Text (ST), and Instruction List (IL).
Let’s take a deeper look into all these PLC Programming Languages.
Once you learn ST, you will never use another language. It is a little difficult to learn if you are not familiar with programming in c or pascal, however once you get it, you can make the same thing like other languages but using just a few lines of code. You can create really complex algorithms, such as advanced PID control, stepper/servo motion control using matrix theory for driving several axis simultaneously (widely used for robotics), manouver variables directly in word data type (memory level) saving cycle time when running big programs, you can read and write data directly from protocol ports (ethercat, modbus, profinet etc), not to mention the integration with image systems. you are not limited to the manufacturer's library and function blocks. You will have the power to modify and create new function blocks based in your needs, edit libraries etc.. You can make things that are impossible in other plc languages. If you are starting to learn PLC and your goal is to become a pro, go for ST language and you will not regret. Other languages like ladder are good for electricians due the way it is written, it is pretty simple and easy for first steps, but as soon you need something more complex such data analysis, dinamic control or advanced motion control, these languages are not good
Once you learn ST, you will never use another language. It is a little difficult to learn if you are not familiar with programming in c or pascal, however once you get it, you can make the same thing like other languages but using just a few lines of code. You can create really complex algorithms, such as advanced PID control, stepper/servo motion control using matrix theory for driving several axis simultaneously (widely used for robotics), manouver variables directly in word data type (memory level) saving cycle time when running big programs, you can read and write data directly from protocol ports (ethercat, modbus, profinet etc), not to mention the integration with image systems. you are not limited to the manufacturer's library and function blocks. You will have the power to modify and create new function blocks based in your needs, edit libraries etc.. You can make things that are impossible in other plc languages. If you are starting to learn PLC and your goal is to become a pro, go for ST language and you will not regret. Other languages like ladder are good for electricians due the way it is written, it is pretty simple and easy for first steps, but as soon you need something more complex such data analysis, dinamic control or advanced motion control, these languages are not good
