Fieldbus Systems
Hard-Wired Connection
Modern machines have many actuators and are loaded with sensors. A control system will therefore have many connections with the machine to convert actuator setpoints and read sensor data. These connections will be mostly electrical wires transporting analog or digital information.
A pure HIL simulator will mimic the plant at the connection level and allow the wires to be switched from the plant IO to the HIL simulator IO. If the HIL simulation has been completed, you switch the wires to the plant and start the machine! There are however some drawbacks:
- The wires transport information at very high frequencies (typically MHz). To mimic this, the HIL simulator has to run at ultra high speeds or use dedicated IO to generate these high frequencies.
- Many IO components are required to connect all the wires.
Fieldbus
Most industrial controllers run at clock frequencies of 50 – 250 Hz. To easily connect IO components with the controller, a fieldbus is used. A fieldbus combines data and addresses to connect multiple IO points. A fieldbus carries information at the same speed as the clock frequency of the controller.
Most HIL simulators directly connect to the fieldbus of a controller. This will reduce the number of IO components to one fieldbus connector and reduce the required speed of the HIL simulator. Controllab can provide HIL simulators for many types of fieldbus systems.