<![CDATA[Purpose – This study develops a PLC-based temperature-control system for a patchouli (Pogostemon cablin Benth) essential-oil distillation condenser. It aims to solve temperature instability while providing an industrial-automation learning platform for laboratory activities.Design/methods/approach – A Siemens S7-1200 PLC, human-machine interface (HMI), PT100 sensors, pump, and cooling fan were integrated into a 170 L condenser tank. Temperature set points of 30, 35, and 40 °C were implemented. PID control at a 35°C set point was evaluated by comparing first-order Ziegler-Nichols tuning with PLC automatic tuning modes.Findings – PT100 sensors demonstrated low mean errors (0.131% and 0.351%). HMI temperature verification remained within the tolerance reported in the original tests. At the 35 °C set point, Ziegler-Nichols tuning yielded Kp = 2.56, Ti = 120 s, and Td = 30 s, with a rise time of 683 s and settling time of 830 s. Automatic tuning yielded Kp = 1, Ti = 20 s, and Td = 0.003 s, reducing rise time to 188 s and settling time to 420 s while maintaining a comparable reported steady-state error.Research implications/limitations – The study is limited to a single laboratory-scale system, focusing strictly on sensor accuracy and closed-loop control responses under specific operating conditions. Future research should evaluate the system's impact on distillate yield, energy efficiency, and specific student learning outcomes.Originality/value – This research bridges process control theory with an authentic energy-conversion application, delivering a practical educational platform using industrial PID temperature regulation.]]>
