A Finite State Machine (FSM) has been developed and successfully implemented. The standard graphical editor DOOCS Data Display (DDD)[2] devloped to display and control the TTF equipment has been extended to allow the creation of FSM designs. From a graphical design window the tool creates a multithreaded C++ code that  is to be run as a state server. These servers automate subsystems and can be displayed and controlled by the DDD tool, like all other devices in the control system. In other words, state machines are an integral part of the Distributed Object Oriented Control System (DOOCS) used at TTF.

Outstanding properties of this approach are:

• a highly modular design, so that new ideas can be incorporated easily
• a graphical design tool with code generator as an integral part of the DOOCS framework
• run-time display of the FSM's status
• implementation of operator proven and optimized procedures

• automated operation of a DSP based low level RF control system for 16 cavities driven by one klystron
• automated operation of the RF gun
• startup of the laser system for the gun

Further information:

Description of the concepts for the FSM

PCaPAC 2000 Paper "An Integrated Finite State Machine to Automate TTF Operation"

Description of the implementation of a FSM for low level RF operation

 PAC2001 Paper: "Finite State Machine Implementation to Automate RF Operation at the TESLA Test Facility" (PostScript)   (PDF)

Short Introduction on the concept of Finite State Machines / Stateflows click here

FSM graphical editor description FSM for dummies

Example 1: A State Machine for the Personnel Interlock system for the TTF Linac tunnel

Example 2: A State Machine for Starting the Laser