Control: SACMI’s choice is PROFIBUS Dp

SACMI has chosen the Profibus system for its machinery electronics control. SACMI latest generation presses for refractories, are thus now featuring Profibus Dp electrical wiring, in addition to other tools already seen on earlier models (self-learning on all pressure and flow control valves in the oil-hydraulic circuit, that is, the possibility of monitoring all the proportional valves that control axes speeds and pressures during every stage of the pressing cycle). With the new inter-component dialogue protocol, a self-diagnosis function that makes identification of any press fault easier has been added.
The main difference between the traditional wiring seen on earlier SACMI presses and the PROFIBUS DP wiring on the latest SACMI presses, lies in the reciprocal positioning of the input/output (SLAVE) system and the control (MASTER) unit.
On presses with wiring of the traditional type, the control unit and the input/output unit are positioned adjacently. With PROFIBUS DP wiring the input/output units are in a decentralised position with respect to the control unit.
The PROFIBUS DP system thus allows the input/output system to be located near the press components (e.g. transducers, actuators, proportional valves), thus aiding localisation of faults.
The fieldbus solution offers two key advantages:
1) a reduction in the cabling that connects the board to the machine because every work unit is connected to the nearest island. Consequently fewer cables are needed to link the electrical board to the machine. In any case the number of cables that connects the island to the sensors and actuators remains the same.
2) the system is expandable and offers an improved capacity to manage later additions / modifications to the machine (e.g. addition of an optional). In a traditional system it is necessary to modify the controller by adding boards, modifying the connection from cabin to optional etc. With the fieldbus system the modification is made on the island to which the optional is connected (even on the island there is a limit to expandability, often dependent on the physical size of the box) but bear in mind that new islands can be added to manage new units, expansions and modifications.