A process in an electro-mechanical system having a plurality of controllable components, is controlled by: (a) storing component objects each corresponding to a component and having activation and/or feedback data for that component; (b) storing operation objects each referencing an operation to be carried out on a component and a pointer to the relevant component object; (c) storing process steps each referring to operation objects; and (d) sequentially processing process steps, by: following each reference to an operation object to determine the operation type and the component object, and performing a data operation to be component object to cause the operation to be carried out on the relevant component. In this way, a system controller can be used to activate components in dependence on the activation state of corresponding component objects and to update the feedback states of component objects in dependence on signals received from the components.