PID controllers generally operate in automatic mode, but most can be switched into manual mode when required.
In manual mode, most controllers operate as follows: The setpoint value is replaced by a % output power value. This value is adjusted using the keypad between 0% and 100% for controllers using single control type, or -100% to +100% for controllers using dual control type.
Depending on the model, auto/manual mode may selected via a dedicated button, from a menu selection, or from a digital input if one is available for this function. Switching between automatic and manual modes is achieved using “bumpless transfer”.
It is possible to use a controller as a “Manual Station. In this application, it is permanently in manual mode.
Caution: Manual Mode should be used with care. In this mode, the PID algorithm is not in control of the process. The output level has to be set correctly by the operator, who must monitor the process for correct operation. Manual power is not restricted by any power output limits.