You have an interesting situation with your use of the RS-232 port for this use. Both CISPR22:2005 (adopted by most countries today) and CISPR22:2008 (the latest revision) gives the same note in the definition of telecommunications/network port saying: "A port generally intended for interconnection of components of an ITE system under test (e.g., RS-232 ...) and used in accordance with its functional specifications (e.g. for the maximum length of cable connected to it), is not considered to be a telecommunications/network port under this definition."
The RS-232 does not define a maximum cable length but instead defines the maximum capacitance that a compliant drive circuit must tolerate. A widely-used rule-of-thumb indicates that cables more than 50 feet (15 metres) long will have too much capacitance, unless special cables are used. I see in Wikipedia that "using low-capacitance cables, full speed communication can be maintained over larger distances up to about 1,000 feet. <http://en.wikipedia.org/wiki/RS-232#cite_note-9> " (Cites a paper by Tony Lawrence.) However, the CISPR22 note indicates that the intention was to not define cabling for interconnection of components of a single ITE system as a telecommunications/network port that would require conducted emissions testing. In contrast, your application of RS-232 does not appear to fit this description. You describe your device as one that "employs multiple RS-232 ports to transfer data to peripheral devices that are dispersed throughout a building which will be accessed by multiple users." This device appears to be fulfilling the role of an Ethernet hub/switch allowing intercommunications and can also allow sharing of printers on the network. The reference is not to the Ethernet protocol but to the purpose & use. As such, your application device seems to fall into the definition "point of connection for voice, data and signalling transfers intended to interconnect widely dispersed systems via such means as direct connection to ... local area networks (e.g. Ethernet, Token Ring, etc.) and similar networks." I did not find any separate definition for "widely dispersed networks" within the CISPR22 standard. You could probably argue the other way by emphasizing the mention of RS-232 in the note, but you will find others that will disagree. Personally, I am not a fan of the telecommunications/network port testing ... especially for products that will not be directly connected to cables leaving the building. If there is a noise issue with a product, it would be picked up by the other traditional tests (power line conducted emissions and radiated emissions). For cables leaving the building, then the risk would merely be to the switch or router that is directly connected to that external cable. I believe it would be extremely rare for an Ethernet line from outside to be connected directly to a server, printer, or other device. Actually, for ports connected to cables leaving the building, I would be more concerned about performing surge testing rather than conducted emissions testing. To best perform this telecommunications/network port conducted emissions testing, test labs are forced to search for custom impedance stabilization networks (ISNs) to support the interface. Otherwise, the alternative test method requires messing up a cable as the the cable insulation is pulled off to get access to individual wires during the test. This does not make anyone happy. Unfortunately, the telecommunications/network port test requirement has been placed in the CISPR22 standard and is being adopted around the world. Monrad Monsen Worldwide Compliance Officer Oracle On 6/11/2010 9:57 AM, Steve O'Steen wrote: I apologize for resurrecting an old string like this but, I’ve encountered a wide variety of interpretations as to what a Telecom Port is in the context of EN55022 and the required testing. One of the latest interpretations I’m struggling with is where the emphasis is on the first statement in the definition “point of connection for voice, data and signaling transfers intended to interconnect widely-dispersed systems via such means as direct connection to multi-user telecommunications networks” The device employs multiple RS-232 ports to transfer data to peripheral devices that are dispersed throughout a building which will be accessed by multiple users. This loosely fits the excerpt above and appears to be the justification for their interpretation. The examples of the “widely-dispersed systems” given in the definition are on another scale and would seem to exclude this type of device. Any comments would be welcome. Steve O'Steen Director, EMC Advanced Compliance Solutions, Inc. [email protected] 770-831-8048 ext. 210 www.acstestlab.com ATLANTA, GA - MELBOURNE, FL - BOCA RATON, FL ****************CONFIDENTIAL**************** This e-mail and any attachments may contain information which is confidential, proprietary, privileged or otherwise protected by law. The information is solely intended for the named addressee (or a person responsible for delivering it to the addressee). If you are not the intended recipient of this message, you are not authorized to read, print, retain, copy or disseminate this message or any part of it. If you have received this e-mail in error, please notify the sender immediately by return e-mail and delete it from your computer. ________________________________ From: [email protected] [mailto:[email protected]] On Behalf Of Monrad Monsen Sent: Tuesday, December 15, 2009 10:32 AM To: [email protected] Cc: [email protected] Subject: Re: Is Infiniband a Telecommunications/Network Port? Peter, I like your conclusion ("Infiniband is not a telecommunication port."), but your justification defeated your conclusion. You stated that "It's akin to an ethernet port." However, CISPR22 clearly identifies "local area networks (e.g. Ethernet, Token Ring, etc.) and similar networks" as a telecommunications/network port in its definition. Therefore, Ethernet is a telecommunications/network port and must be conducted emissions tested. My point is that Infiniband cannot run on long cables (100 foot or more plus infrastructure to go building, campus and worldwide through hubs/switches/routers). Monrad L. Monsen Worldwide Compliance Officer Sun Microsystems [email protected] 303.272.9612 Office Peter Tarver wrote: Monrad - Infiniband is not a telecommunication port. It's akin to an ethernet port. Peter Tarver [email protected] Would it be correct to not classify Infiniband as a telecommunications/network port under CISPR22? snip< -- Monrad L. Monsen Worldwide Compliance Officer Sun Microsystems [email protected] 303.272.9612 Office - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher <[email protected]> David Heald <[email protected]>
