Glossary · PLC and control programming
PLC programming
Also known as: Controller programming, PLC software engineering
German: SPS-Programmierung
In industrial automation, PLC programming is the creation, testing and maintenance of control programs for programmable logic controllers, typically in the languages of IEC 61131-3 and in the vendor's engineering environment.
- PLC programming
In one sentence
PLC programming creates, tests and maintains control programs for PLCs, usually in IEC 61131-3 languages.
Example
A controls engineer programs the logic of a palletizer in structured text and ladder diagram, tests it on a virtual controller and commissions it on site.
How it applies
- Engineering: PLC programming covers hardware configuration, data structures, program logic, communication, alarms and HMI interfaces. Choosing the right language per task, such as ST for calculations, LD or FBD for interlocks and SFC for sequences, keeps programs maintainable.
- Commissioning: Programs are finished and adjusted on site. Changes made there must flow back into the archived project; otherwise the next download overwrites them.
- Safety: Safety-related logic runs on safety controllers with their own programming rules, restricted languages and verification requirements. Standard PLC logic must not be relied on for safety functions unless it meets the applicable standard.
- Documentation: Good PLC programs document themselves partly through names and comments, but not completely. The documentation team needs the I/O list, alarm list, operating modes and state descriptions from the programmers to write accurate operating and service manuals.
PLC programming vs. software development
PLC programming is a specialized form of Software development, shaped by real-time cyclic execution, direct hardware interaction and long machine lifecycles. General software practices apply, adapted to these conditions.