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Industrial plasma processes with CANopen

Plasma products from Relyon Plasma are equipped with a CANopen interface. This is realized with an HMS protocol stack. In combination with Anybus gateways for CANopen, they can be embedded into diffferent network environments.

Multi-channel process: 5-plasma generators (type PN3) in compressed-air operation (Photo: Relyon Plasma)

Requirements for ease of integration of plasma products used for surface treatment have increased steadily. Various communication standards have been established at the international level. At the same time, customers in the packaging or automotive supply industries demand a cost-efficient and robust standard solution that can be integrated into any specific plant technology. For this reason, Relyon Plasma implemented a CANopen slave interface using an Ixxat protocol stackby HMS. When combined with a Anybus X-gateway CANopen (master), Relyon Plasma can be used with any system configuration.

Atmospheric plasma is one of the most efficient methods for treatment of materials to create ideal conditions for subsequent processes such as gluing, laminating, or varnishing. Product quality is improved while increasing throughput and without using additional primers. Another important topic is the germ-reducing effect of plasma in the pharmaceutical industry and in food engineering. An electric discharge can generate an intense atmospheric plasma jet in air streaming out of a nozzle. The company uses high-frequency pulses from a high voltage source and a nozzle designed specifically for this purpose.

The PS2000 high-voltage supply with PB3 plasma generator and 10-m drag-chain-compatible HV cable (red) and compressed air connection (blue); CAN interface (CANopen slave) (Photo: Relyon Plasma)

Communication is essential for controlling this type of high-performance system. Using CAN, several plasma channels, temperature, and pressure sensors, as well as mass flow controllers can be connected in a production plant such as those used in the packaging industry. The CAN network offers up to 127 addresses per node and delivers transfer rates up to 1 Mbit/s with 40 m or 500 kbit/s with 100 m cable length. Communication via CAN is outstanding in terms of tolerating electromagnetic interference, said the company.

Cross-vendor standard

In production plants, self-contained isolated solutions or analog control system interfaces have long since ceased to be “state-of-the-art”. Secure communication as a redundant system to the emergency-stop circuit is helpful, not least for meeting the required performance level, risk classification according to ISO 13849 standard. The Relyon high voltage source is capable of deactivating the active high voltage by way of a hard-wired emergency-stop circuit and the CAN interface.

In either case, communication and status monitoring continues without interruption. The plasma system must be embedded into the primary control system design. To be sure, communication standards differ based on industry, region, or type of plant control system used. Although the open communication protocols Devicenet or CANopen based on CAN are available, they are not supported by all control system solutions. In this case, users can implement solutions for integration. Starting with a laboratory system controlled via CAN/USB module directly with a laptop, through to a fully automated production plant with central control system, and continuous transfer of all process parameters to the factory information system.

Anybus X-gateways are used when the goal is to integrate CANopen field devices into primary fieldbus or industrial Ethernet networks: for instance into Devicenet, Profibus, Profinet, Ethercat, Ethernet/IP, etc. The gateway is mostly used as the CANopen manager, but is also capable of CANopen-slave functionality. The Ixxat CANopen protocol software allows implementation of CANopen functionality directly on customer hardware. The software includes the functions for realizing CANopen NMT-slave or CANopen NMT-master devices as defined in CiA 301 and the CiA 302 series.


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Relyon Plasma