In a control system, when a sensor receives a sensing signal, the sensor sends a notice signal to a preparatory starting device so that the preparatory starting device performs a starting operation. After the starting operation is finished, the preparatory starting device sends an operation command and/or operation power to a starting unit. The starting unit would not pass the operation command and/or the operation power to a receiving end until receiving a control signal.

A field device with a microprocessor and a display and/or operating module, which can be disconnected from the field device, with the microprocessor showing an energy saving module, in which the display and/or operating module are switched off, with the waking circuit being provided, which generates a waking signal when the display and/or operating module are disconnected from the field device or connected thereto.

A diagnostic device is physically coupled to a control device in a process control system, and includes an accelerometer that determines when a motion or vibration of the control device is greater than a predetermined threshold. When this condition is detected, one or more other components of the diagnostic device (e.g., processor, communication module, etc.) are activated, and a distress signal is transmitted from the diagnostic device using the activated components. Consequently, the duty cycles of components of the diagnostic device are decreased and optimized, leading to significant power savings. Indeed, in some embodiments, energy harvesting may be sufficient to power the diagnostic device. Further, in some embodiments, the diagnostic device may not require a component processor.