PLC programming

Short definition

PLC (programmable logic controller) programming or PLC programming refers to the creation of control software for industrial automation systems. It enables the cyclical processing of sensor and process data and the resulting control of actuators, valves and drives. Programming is carried out in accordance with IEC 61131-3 in standardized languages such as ladder diagram (LD), function block diagram (FBD), instruction list (IL) or structured text (ST). In membrane filtration, the PLC controls all process-relevant parameters and sequences.

Functional principle

The PLC works according to the EVA principle (input-processing-output) in defined cycle times. Sensor signals such as flow rate, pressure and temperature are read in, compared with the programmed algorithms and converted into control commands for pumps, valves or frequency converters. Modern PLC systems such as Siemens S7-1500 or Beckhoff TwinCAT integrate safety functions, diagnostic routines and communication interfaces to higher-level SCADA or MES systems. Programming is carried out in development environments such as TIA Portal, CODESYS or Studio 5000.

Areas of application

PLC programming is at the heart of every automated membrane filtration system. It controls critical process sequences such as filtration, backwash and CIP cycles, monitors limit values and optimizes energy consumption using adaptive algorithms. The integration of predictive maintenance and data logging enables process optimization and fault diagnosis in real time.

Typical areas of application:

• Ultrafiltration and nanofiltration systems
• Automated cleaning processes (CIP/SIP)
• Crossflow control and transmembrane pressure control
• Batch management in pharmaceutical production
• Energy and resource management in water treatment plants

Summary

Professional PLC programming ensures reliable, reproducible and efficient process sequences in membrane filtration. It reduces downtimes, minimizes operating costs and meets regulatory requirements such as FDA 21 CFR Part 11 or GAMP 5. For plant manufacturers and operators, it is the prerequisite for economical automation solutions with high plant availability and long-term maintainability.