Festo's on-going development of the compact performance (CP) series of valve terminals has led to the release of the actuator/sensor interface (AS-Interface), a simple open bus protocol which offers considerable opportunities for savings and is especially advantageous when used with actuators and sensors dispersed over a wide area. Pneumatic systems benefit from the decentralisation of the I/O level, the high speed of data transmission, the short reaction times for actuators and the low installation costs. In addition to Midi and Maxi valve terminals with AS-Interface, Festo now offers AS-Interface technology for its biggest-selling valve terminal of recent years, the CP series. The CPV valve terminals are a successful fusion of maximum performance, minimum dimensions and an attractive price/performance ratio with integrated additional functions. The smallest version, with valve modules only 10 mm wide, provides nominal flow rates of 400 l/min and is very compact, particularly with the new flat-style silencers. CPV valve terminals with AS-Interface are available with up to eight valves and up to eight sensor inputs for direct mounting on a top-hat rail.
This CPV valve terminal has four or eight binary sensor inputs on the top of the terminal and up to eight solenoid coils as outputs. In terms of the AS-Interface network, two cylinders controlled by bistable valves and with end-position sensing at both ends correspond to one station. It is thus possible to equip each of these AS-Interface slaves with eight mono-stable valves or four bi-stable valves or a mixture of four mono-stable valves and two bi-stable valves. This configuration precisely corresponds to two AS-Interface slaves, which can be addressed individually. A terminal equipped in this way can control up to eight double-acting cylinders and monitor their end positions. This illustrates the networking potential which CPV valve terminals offer, namely that 124 valve coils per master can be integrated into an AS-Interface network, which can accommodate up to 31 stations/slaves, a figure which is soon reached with large automation projects. There is a clear trend today towards modules with eight inputs and eight outputs, which makes it possible to provide decentralised control and position sensing for simpler handling tasks.
Further advantages of Festo's AS-Interface-compatible CPV valve terminals with four inputs/four outputs or eight inputs/eight outputs include two sizes for standard nominal flow rates 400 and 800 l/min, with a facility for division into pressure zones with pressures of 90 kPa to 1 Mpa (0,9 to 10 bar); momentary-contact or detenting manual overrides; 40 µm degree of fully adequate filtration; additional power supply for safe emergency stop or restart behaviour; IP65 protection with a 100% duty cycle. Up to 25% shorter switching times can be achieved by using the F module with the CPV 10 series. Integrated vacuum is provided by vacuum generators with various flow rates, such as the CPV 10 with 70 l/min and the CPV 14 with 95 l/min.
Valve terminals with AS-Interface are supplied in turnkey form, ready to install, fully tested and fieldbus-compatible. Valve terminals of this type include CPV terminals and Midi/Maxi valve terminals with valves of different widths and ISO valve terminals. An AS-Interface master used as a terminal module acts as the interface between the AS-Interface network and the master field bus system, such as Interbus or Profibus.
If it is necessary to integrate a single cylinder with a solenoid valve into an AS-Interface network, the easiest solution is to fit a combi socket onto the coil plug to act as an interface. These sockets, available with or without sensor inputs for cylinder switches, are compatible with the DIN 43650 connector pattern and other Festo solenoid coil plugs. This allows individual valves, larger ISO valves with flow rates up to 4500 l/min or start-up valves on service units to become AS-Interface stations. Numerous other components that are available, including the AS-Interface combi power supply unit, addressing units and flat-cable sockets, assist users to create their own custom installations on the basis of Festo's modular AS-Interface system.
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