Runnable simulator field guide
Fermentation-temperature PLC scenario: test checklist
Direct answer
The learner can keep heating and cooling mutually exclusive, use stable control bands, detect failed response and retain temperature evidence across a batch.
Written for process-control learners sequencing a slow thermal vessel with sensor quality, setpoint bands, heating, cooling and abnormal response.
Scenario setup
Batch phase, temperature sensor and quality, setpoint, heating and cooling bands, minimum timing, actuator proof, high and low alarms and record interval.
I/O and state map
Vessel temperature through sensor, scaling, controller state, heat or cooling command, utility response, process trend, alarm and batch record.
Normal run
Temperature remains within the declared band without conflicting outputs while commands produce the expected directional response.
Boundary run
Bad sensor, high ambient load, slow cooling, stuck heater, both requests, setpoint change, power return, manual mode and incomplete batch record.
Injected fault
A process, sensor, scaling, control-state, command, utility, actuator, alarm or record mismatch.
Target check
The control strategy validated against current process, quality, equipment, hygienic and safety requirements.
How should heating and cooling be interlocked?
Use exclusive state ownership plus suitable deadband and minimum timing, then test simultaneous demand, mode changes and failed feedback explicitly.
What evidence should a fermentation temperature record retain?
Record batch identity, timestamped temperature and quality, setpoint, control mode, heat and cooling commands, alarms, interventions and exceptions.