Combining

Devices and CANopen

Whenever data needs to be communicated between a serial bus system and Ethernet, gateways provide the bridge. This solution is controlled via TCP/IP and supports CANopen PC cards as DIN-rail mountable devices.

CANopen Ethernet

Author ethost, the latest gate- replacement for conven- er level of performance not way from Hilscher, of- tional integrated serial bus often needed. Nfers a totally different system solutions. „Does it always need approach to convention- to be industrial-standard al solutions. Controlled Ethernet and Ethernet? In most cas- via native TCP/IP, it sup- so-called es, maintaining the serial ports the full feature set hand in hand bus system still in combi- of Hilscher’s standard nation with the simple of- CANopen PC card in ac- The use of Ethernet for es- fice-standard Ethernet cordance to CiA 301 but as tablishing a modern com- results in a sufficient so- Armin Beck a DIN-rail mountable de- munication infrastructure lution too,“ commented Hilscher GmbH vice. offers high potential sav- Armin Beck, product man- Product Manager „It controls 1000 ings. Transparency of the ager for gateways at Rheinstraße 15 CANopen I/O's within a system, uniform wiring Hilscher, on the seemingly DE-65795 Hattersheim millisecond without re- standards, simple redun- inevitable change. Indeed, Tel.: +49-6190-9907-0 quiring an own designat- dancy concepts to avoid it can make sense to con- Fax: +49-6190-9907-50 ed CANopen connection”, downtimes and short pro- tinue using the potential of [email protected] would be a convincing ad- cessing cycles in combi- the already available serial vertising message for a nation with high determin- bus system. For example, Link PLC system offering only istic are only some of the strict real-time response www.hilscher.com an Ethernet interface by advantages of the Industri- is usually only required design, while still provid- al Ethernet. Unfortunately by motion control applica- ing full access to CANopen though, machine designers tions. In more than 95 % of CAN Newsletter Online nodes devices. Nethost have to choose between 6 all other applications it is CANopen in industrial automation is „hosting“ the missing different completely irrelevant. Pro- CANopen interface as an protocols competing on the cessing cycles lower than Ethernet node. Thanks to market in the meantime. a millisecond is only in very the simplicity of the TCP/ Implementing and support- few cases required. Neth- IP protocol and the high ing any of them calls for ost is a feasible solution transmission range of 100 high up-front investments for all applications, where Mbit, this is a suitable in order to gain just a high- machine control via serial

24 CAN Newsletter 3/2014 Projekt1 17.07.14 13:58 Seite 1 bus system has proved to be a reliable concept and now intended to be op- erated remotely via Eth- ernet. It offers latency as low as 1 ms and the sup-

Devices port of simple TCP/IP. The bandwidth of the 100 Mbit Ethernet is sufficient to al- low safe simultaneous ad- dressing of up to five such devices via one Ethernet line, which was proven by measurements.

Protecting investments in serial bus system devices

When looking at its sales history, Hilscher observes a clear trend towards Eth- ernet. Demand has ris- en considerably especially during the past two years. Figure 1: The Nethost enables PC card ‘slot-less’ compact industrial PCs or other Yet, with a market share of embedded systems connectivity to and control of serial bus systems over Ethernet over 70 %, serial bus sys- (Photo: Hilscher) tem technology still holds a strong position and will one by one, enabling its re- Supported are SDO com- example CiA 309 does not continue to exist for many mote control over Ethernet. munications and NMT cover, bringing the underly- years. This also means that Nethost, however is differ- master operations. Nodes ing CANopen system into a machine manufacturers will ent and not just a simple emergency messages are safe state when the Ether- need to support both sys- server. It includes a fully collected node wise in diag- net application dies. tems for quite some time, featured CANopen master nostic buffers requestable The coding logic is which the company took as that runs autonomously by the Ethernet applica- provided by Hilscher as a special challenge. „When and takes care of all config- tion as well. If necessary part of a C source code. discussing the concept for ured transmit- and receive- is it also possible to trans- It is projected to a socket the new product, protect- PDOs of its nodes by itself. mit and receive pure CAN interface and is therefore ing investments was of pri- All these PDOs then are of- telegrams to the network at compatible with any TCP/ mary importance to us,“ fered in a compressed pro- any time by using COB-ID IP stack. On the side of the stated Beck and added: „It cess data output and input filtering. application, it is abstracted was therefore not our goal image, a single Ethernet to a simple procedural se- to simply replace the seri- service grants access to. Short time-to-market rial bus system indepen- al bus system with indus- With the simplicity of this dent API interface. Simple trial Ethernet. Instead, we interface a Nethost user TCP/IP as such takes care functions, such as open, wanted to combine both needn’t care about all the of safe transmission from close, reset, send, receive technologies in a simple CANopen services, the pro- and to the Nethost. The or I/O-exchange guaran- way to address a wider tocol handling and the con- transparently transmitted tee a fast learning curve market and allow custom- figuration. This enables the telegrams are coded and to allow shortest-possible ers to continue using prov- effortless integration into classified depending on integration times. Based en field devices.“ The ide- conventional PLC systems their purpose, adding only upon the RPC principle, al of a gateway based upon used to operate with cyclic a few bytes to the header functions are decoded in- TCP/IP was born. IO images anyway. Nethost of the telegram. The cod- side the device and pro- The CiA organization furthermore maintains no ing is Hilscher specific. Us- cessed remotely. In order as well took account of the CANopen object diction- ing the standard proposals to make it easy for embed- Ethernet trend and devel- ary to be configured over CiA 309-2 or CiA 309-3 for ded programmers as well, oped the standard CiA 309 CiA 309 services. Much encoding the services over a DLL allows immediate dealing with the subject of simpler: the configuration TCP or ASCII does use of the Nethost under “Interfacing CANopen with is done as a whole and in not go far enough. Nethost Windows, while a C toolkit TCP/IP”. As an immedi- one step with a graphical is pursuing a global and se- shows a sample implemen- ate result, a few Ethernet configuration tool. rial bus system indepen- tation under Linux. to CANopen gateway serv- Apart from the PDO dent approach over all its The Nethost’s API ac- ers emerged on the market transmissions the CANopen supported serial bus sys- cess functions confirm to redirecting and forwarding Nethost supports various tems such as , De- the Hilscher platform strat- TCP/IP coded CANopen CANopen specific servic- vicenet and CANopen. A egy and follow the basic commands to the under- es as well that can be in- Nethost supports a watch- principle „once installed – lying CANopen system structed over Ethernet. dog function, which for everything works“ just like

26 CAN Newsletter 3/2014 C M Y CM MY CY CMY K

with Hilschers PC cards. Future steps For example, exchanging the Windows PC cards DLL The next step of the devel- against the Nethost DLL opment of Nethost is al- allows exchanging both ready under way. In the 3rd product ranges without any quarter of the year, Hilscher need to change the appli- will present three new mod- cation program. Both DLLs els of its Nethost range on have the same API. What- the market. The already ex- ever was formerly con- isting models for CANopen, trolled locally over a PC, Profibus, and Devicenet can now be controlled re- will be complemented by motely via Ethernet direct- models for Profinet, Ether- ly from the process control cat and Ethernet/IP Master. level. „Using the same API In this way, Hilscher reacts turns Nethost into a ded- to an increased demand for icated PC card for the TCP/IP applications in the switching cabinet. For sys- real-time Ethernet world. In tems without PC card slots, general all models are con- it even turns into a direct re- figured via a serial bus sys- placement for PCMCIA PC tem-independent uniform cards for example,“ Beck FDT/DTM-based configu- commented on the access ration tool. In situations, via the Ethernet and added: where an engineering tool „And if a system already of the target system al- supports our PC cards, ready exists, open config- it will automatically also urations via standardized support the operation of a XML files are an alternative Nethost.“ offering increased trans- Hilscher was able to parency. XML schemes win two of its long-stand- turn the configuration data ing customers to integrate into the correct format and Nethost into their solutions. can be loaded into the Net- For many years, these host after conversion into companies had ordered a binary file. In this way, high quantities of PC serial the device can be fully bus system cards to control integrated into any target their peripheral compo- system. nents. After 15 years, how- ever, both of them announced to work on a new generation control so- lution, which offered more compact dimensions in combination with increased flexibility, but could only be addressed via standard Ethernet interfaces. Yet, they did not want to give up support of established se- rial bus system technology and looked for a migration path to their new product generation. Using a con- ventional TCP/IP stack and a standard Ethernet controller, while utilizing existing programming ex- perience, these companies were able to offer system integration within a mini- mum of time. Today, they are in a position to serve both the existing base of serial bus system custom- ers, as well as new Ether- net customers.