Short definition
Programmable controllers, also known as programmable logic controllers (PLCs), are industrial automation devices for controlling and regulating technical processes. They process digital and analog input and output signals according to freely programmable algorithms in real time. PLC systems are characterized by their robustness, real-time capability and modularity. In membrane filtration systems, they form the central control element for pumps, valves, sensors and the coordination of all process sequences from filtration to backwashing and CIP cleaning.
Functional principle
The PLC works according to the cyclical processing principle: reading in the input signals, processing the user program, outputting the control signals. The program is created in accordance with IEC 61131-3 in standardized languages such as LD (ladder diagram), FBD (function block diagram), IL (instruction list) or ST (structured text). Modern PLCs integrate function blocks for control, motion control, safety and communication. Programming is carried out in development environments such as TIA Portal (Siemens), Studio 5000 (Rockwell) or CODESYS. Diagnostic functions, online monitoring and remote access support commissioning and maintenance.
Areas of application
PLC systems are the backbone of every automated membrane filtration system. They control sequential process sequences, implement complex control tasks and coordinate communication between the field level and higher-level systems. Redundant PLC configurations ensure maximum availability in critical applications. Safety PLC modules fulfill safety functions up to SIL 3 according to IEC 61508.
Typical areas of application:
- Fully automated UF/NF/RO filtration systems
- Batch control in pharmaceutical processes
- CIP sequence control with phase management
- Multi-stage filtration systems with process coordination
- Decentralized control architectures with remote I/O
Summary
PLC systems are indispensable for reliable, reproducible and efficient automation in membrane filtration. They offer maximum flexibility through free programmability and meet the highest requirements for availability and safety. For plant manufacturers, they mean standardized, maintainable solutions with long-term spare parts supply and comprehensive engineering support.
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