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Industrial Protocol Activity
Bill Lydon attended the recent annual ODVA meeting in Phoenix Arizona. ODVA is a not for profit industry trade group with over 270 members that develops and promotes industrial communication protocols, DeviceNet was the fist network introduced.
The ODVA was founded in 1995, is an international association comprised of industrial automation companies. Collectively, ODVA and its members support network technologies based on the Common Industrial Protocol (CIP™). The CIP is a unifying object model for all ODVA protocols. These protocols currently include DeviceNet™, EtherNet/IP™, CIP Motion™, CIP Safety™ and CIP Sync™. ODVA manages the development of these open technologies, and assists manufacturers and users of CIP Networks through tools, training, conformance testing, and marketing activities. ODVA also is active in other standards development organizations and industry consortia to drive the growth of open communication standards.
Hot topics from the ODVA meeting were the introduction of the new CompoNet™ network, and developments in CIP Sync™, CIP Motion, and CIP Safety™ There was a strong theme of Ethernet for automation and control driven by ODVA standards.
“NO SPECIAL SILICON” is the “big idea” ODVA is promoting for Ethernet based controls and automation. Industrial application of Ethernet is a huge growth area that everyone in the industry wants to exploit. If the ODVA Ethernet based protocols for motion and time synchronization work as advertised they will be useful for most applications. This does not mean they will be sold for all applications since marketing, sales, and nationalistic factors will shape adoption. This is will be debated and argued for a long time.
The ODVA’s major claim is all protocols are based on the CIP object model insuring compatibility and particularly the functionality of routing messages between CIP based networks.
ODVA’s Common Industrial Protocol (CIP™) does seem to provide a unifying mechanism between ODVA networks that is being proven.
CompoNet™ is a network for, "applications dominated by sensors and actuators", to compete with networks such as ASi and cc-Link LT. Omron developed the technology. A four wire flat cable with a clever connector was introduced with CompoNet™. The connector is an IDC (Insulation Displacement Connector) that clamps on the cable and has an integrated pluggable IDC connector for network drops. This is a master/salve protocol supporting transmission speeds up to 4 M bps. The protocol supports bit, and word (16 bit) slaves.
CompoNet conforms to the CIP model allowing “nodes to communicate with DeviceNet and EtherNet/IP seamlessly”.
The AS-Interface (ASi) is the established network for low level devices with CompoNet™ as a late entry. ASi has a very refined cabling system using flat cables and piercing connector technology with products designed for this cable system from a wide range of vendors.
ASi has also addressed safety with the AS-Interface Safety at Work System allowing safety components to be integrated into an AS-Interface network. Safety and standard components work in parallel on the same cable. To be competitive I think ODVA will likely address safety with CompoNet.
ODVA and other network standards organizations in the past seemed to have the attitude that ASi was just a low tech and slow bus that was not really important. ASi has been penetrating the market and has some real benefits in installation.
Will the CIP Advantage overcome the momentum of ASi?
CIP Safety™ has been approved by TÜV for use with DeviceNet and EtherNet/IP™ making the approval process for CIP Safety™ products simpler and faster. The basis for this is the Common Industrial Protocol model that is the higher level protocol stack independent of media type.
Eighteen DeviceNet CIP Safety™ products from three vendors are shipping today. EtherNet/IP CIP Safety products should be available in late 2006.
The TÜV certificate validates the CIP design concept as a Common Industrial Protocol based on a top down modular design. The opportunity for safety systems is large now that open architectures can go after the market with changes to safety standards. The leading contenders are AS-Interface Safety at Work, CIP Safety™, and ProfiSafe.
A CIP Safety™ paper was presented at the conference illustrating an EtherNet/IP to DeviceNet "linking device", basically a bridge and router. In addition methods are being studied for detecting duplicate IP addresses in safety networks.
The unifying CIP architecture may provide ODVA an advantage….
The adoption of safety network protocols is likely to be geographic based on the market strength of major vendors similar to the adoption of DeviceNet and Profibus.
CIP Safety™ for DeviceNet I/O
I picked up a data sheet titled " CIP Safety™ for DeviceNet I/O Toolkit at the conference that has three vendors’ names at the top, OMRON, SICK, and Rockwell. This is a toolkit to create CIP Safety device. The Rockwell sales person told me they were encouraging companies to develop safety products.
The first two toolkits are expected to release in May of this year (I/O Toolkit and Low-End Adapter Toolkit). They will be licensed via specially appointed "Safety Value Added Resellers" or sVARs. The sVARs will be responsible for sales, marketing, support and, possibly, development assistance with the toolkits.
This strategy is aggressively pursued will help to proliferate the CIP Safety™ standard.
EtherNet/IP CIP Motion
EtherNet/IP CIP Motion is based on extensions to the CIP protocol to insure compatibility with other CIP based protocols. EtherNet/IP CIP Motion nodes receive time stamped data to synchronize network nodes and use an extrapolation polynomial allowing devices “to ride through late data conditions”. This allows CIP Motion to use standard 100 Base T full-duplex switched Ethernet using QoS functionality , as defined in IEEE 802.1Q.
The heart of CIP Motion is an architectural departure from protocols such as SERCOS that synchronizes nodes with hard timing techniques. This brings to my mind a number of questions based on my experience with multi-axis machine tool controls and industrial networks. I have to say the “jury is out” until real applications can demonstrate the capabilities and limits of EtherNet/IP CIP Motion.
CIP Conformity Club
The CIP Conformity Club was announced and a number of companies inducted into the club.
ODVA was criticized in the early days for compatibility problems between vendor products. The ODVA has done a great deal of work in this area and it shows. The plug fests have been extremely effective as a way for vendors to identify and work out compatibility problems.
The CIP conformity club is a way to recognize companies that are committed to compatibility.
Gigabit Ethernet, A Paper was presented by Rockwell people about their testing of Gigabit Ethernet over four pairs of category 5 balanced cable. This approach uses a daisy chain approach to "eliminate switches".
A major problem with Ethernet for general controls is the added installation cost of the wiring configuration. Multi-drop networks dominate the general controls architectures (Modbus, AB Data Highway, Profibus, ASi, CAN, etc.) This may be the beginning work to solve this issue.
November 16, 2005 ODVA announced that CISCO became a founding member of ODVA. CISCO views industrial as a growth area and it fits into CISCO’s view that network infrastructure in all buildings is becoming a basic utility. VOIP phones are also a key part of this network utility.
CISCO is covering the bases just as Microsoft does with industrial automation being another check mark. Microsoft’s goal is to have every computer in the world running Microsoft; CISCO’s goal is to dominate anything related to IP. CISCO is also a member of the Fieldbus Foundation and is a Rockwell Encompass partner.
Some CISCO customers are using IP phone as low end HMI devices since they have displays and are WEB enabled. Interesting twist…
Filed Device Tool (FDT)
A specification has been completed to conform with FDT (Field Device Tool). FDT technology standardizes the communication interface between field devices and systems. The key feature is its independence from the communication protocol and the software environment of either the device or the host system. FDT allows any device to be accessed from any host through any protocol.
Having a common configuration tools is a great idea and it looks like it is actually going to happen in the industrial market.
PoE (Power Over Ethernet)
There was a brief presentation on Power Over Ethernet and I was in a couple of side discussions with people sharing ideas about POE. People feel it would be an advantage but the total amount of power available is the major issue. Other concerns I heard were cabling and IP67 connector issues.
The idea of the Ethernet cable also being the power cord has a great deal of appeal emotionally to engineers. There are electrical code limits that need to be considered or the installation may require electricians. For example DeviceNet uses NEC class II power limited to 100 VA with a maximum current of 4 amps. My guess is an ODVA SIG will be started on PoE.
About the Author
Bill Lydon is an industry analyst & business consultant to the building, industrial, and process controls industry. Bill has a broad background in Building Automation starting at Johnson Controls designing Building Automation Systems, DDC products, and as product manager. Subsequently Bill co-founded and ran an object oriented control software company. Bill presently consults to the Building Automation and industrial controls industry.
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