mg_stateedit provides a graphical editor for the DAQ manager state machine. When invoking the command a single command line parameters is required, the path of the configuration database file.
A state machine consists of a set of defined states and their legal successor states. The process of the state machine changing state from one state to another is called a transition. In the DAQ manager, these transitions can trigger the execution of sequences, which must succeed for the transition to succeed.
Before describing the interface, some terminology. The states the state machine can transition to from any givnen state are called Successor States. The states from which a state can transition to are called Precursor States. The process of defining a state machine is that of defining the states and, for each state defining its successor states. In some cases, it's also convenient to define a state's precursor states. The mg_stateedit command allows for both.
The window resented by mg_stateedit is primarily composed of three list boxes. The center list box lists the defined states selecting (single clicking) a state in the States list box populates the left listbox with that state's precursor states and the right list box with that state's successor states.
Below each list box is a button. Clicking that button when a state is selected in any list box removes that state from that listbox:
Clicking that button below the middle listbox removes that state's definitions (cleaning up all transitions to that state from precursor states and all transitions to successor states as well).
Clicking that button below the left listbox removes that state from the precursor states of the selected state in the middle listbox. This removes the allowed transition from the precursor state to the selected state.
Similarly, clicking that button below the right list box removes that state from the successor states of the selected state in the middle listbox. This removes the allowed transition from the selected state to that successor state.
Below the buttons below each listbox are text entry widgets and a button.
To add a new state, type a unique state name in the middle entry and click its button.
To add a new precursor state to the selected state, type the name of an existing state in the left listbox and click its button. The state must be defined or an error will be displayed.
To add a new successor state to the selected state, type the name of an existing state in the right listbox and click its button. Once more the state must already be defined or an error will be displayed.
Note that all changes change the underlying database immediately.