Two-Tank Level Control System (Beckhoff TwinCAT)

The application itself was straightforward: monitor and control liquid level across two tanks in a food and beverage production process, opening and closing solenoid valves to manage fill and drain based on level. On its own, a task like this would typically be handled with float switches and a basic relay or timer-based control panel, with no PLC required.

Thomas Hadden specified a Beckhoff CX8190 embedded PC with an EK1100 EtherCAT coupler and EL-series I/O terminals instead, deliberately taking the system beyond what the immediate control task demanded. The driver was the customer's stated intention to expand the system into their wider site SCADA architecture at a later date. A relay panel would have solved the level control problem in isolation, but it would have left the customer with a dead end: no structured data, no communication protocol, and no straightforward upgrade path.

Level sensing was handled with ifm LR9020 capacitive rod probes, cut to length for each tank and paired with ifm level amplifier modules to convert the probe signal into a usable 0-10 V setpoint range for the control system. This approach gave continuous, adjustable level feedback rather than the simple high/low switching a float-based system would provide, which in turn supported tighter control of the fill and drain cycles on each tank.

On the output side, the valve switching was built around a structured contactor arrangement rather than direct wiring, keeping the panel modular and each valve circuit independently identifiable and serviceable. This mirrors an approach Thomas Hadden has used on other panel work: structured, labelled wiring pays for itself in fault-finding time, even on a system this size.

The result is a level control system that does its immediate job, reliable two-tank level management on a food and beverage line, while giving the customer a genuine, low-friction route into SCADA integration when they're ready for it, rather than a self-contained box that would need replacing to get there.