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DEVELOPERS' FREQUENTLY ASKED QUESTIONSWhat is the rationale behind the requirement that 4-pin and 6-pin sockets can not be on the same platform? Answer How to obtain a 1394 Vendor ID Answer We are planning to install wiring to use 1394b protocol-based equipment in the near future. Should we install UTP or Fiber optic cable? How many wires? Answer Where can I get a detailed description of the DV Standard? Answer Has the Digital Video copy protection problem now been resolved? Answer What about protection for content coming into the home or office? Answer Does 1394 have a formal name? Answer Where can I obtain a copy of the specification? Answer What is the status of 1394a, and what does it achieve? Answer What is 1394b, and is it available? Answer What kind of bridging work is now underway to enable the use of 1394 in networking applications? Answer How does the 1394 bus compare to USB, SATA, HDMI or Fiber Channel? Answer Is 1394 a good fit for industrial applications? Answer What other applications can 1394 be used for? Answer What about 1394 peripherals? Answer Where can I find out about 1394 training programs? Answer Is there a basic list of 1394-based equipment and products now available? Answer Are there any books available about 1394? Answer Six-pin sockets provide power, 4-pin do not. A node can either be a power provider, a power sink or neither. There is no way for a node to identify itself as one that provides power out one port but not another. In addition, when there are two or more sockets on a node, power is either passed from one socket to the other or not. There is no way to be able to identify which sockets pass power and which do not. For example, if you had a four port node and two ports had 6-pin sockets and the other two had 4-pin sockets there would be absolutely no way for the bus manager to know that power is not passed through all sockets. So, why, one may ask, is this all so important? Well, when endeavoring to create a bus manager that has power distribution management (PDM) capability, there must be a mechanism by which the PDM can determine the source of power and where and how that power is delivered to other nodes. The Cable Power Distribution (CPD) Specification has gone to great lengths to make certain rules exist that enable good power distribution. Why? Because it has been found in 1394-1995 implementations that nodes that attach to the bus and simply receive a link-on with no forethought to power management cause bus failures when a link-on causes too much power to be extracted from the power provider - causing voltage droop, power brown-outs, etc. Now that all of this has been said, it is important that I inform you that there is work being done in the Power Distribution Management Specification that may, in fact, create an opportunity for an OEM to have a mixture of 4-pin and 6-pin sockets and eliminate the need for the constraint set forth in the CPD spec. For example, an OEM may implement 1394b and have a GOF socket and a 6-pin socket. In this implementation, the same issue exists - one has/passes power the other does not. So this problem had to be solved. Here is what is being done to solve the problem. Any node that has a mixture of like-media sockets must declare their power class field in their self-ID packet to be power class four. This requires such nodes to have a link and to have CSR space. CSR space must contain registers that identify port capability. One of the port capabilities that shall be identified are where a port consumes power, sources power, and passes power or not. BUT, since PDM has not yet been ratified, the CPD specification is the "standard" OEM's must abide by. How to obtain a 1394 Vendor ID If you are creating a new 1394 product, you should have a vendor ID from the IEEE so that you can properly identify your product in its Configuration ROM. The URL below has all the information you need: http://standards.ieee.org/regauth/oui/index.shtml The IEEE 1394b-2002 specification describes the cabling which can be used. The standard provides three long-distance options, and you may have additional vendor-unique choices if you agree to use the same vendor's hub or repeater at both ends of the cable. The standard options are UTP (Category 5 Unshielded Twisted Pair), POF (Plastic Optical Fiber), and GOF (Glass Optical Fiber). The available distance and speed (and price) depend on the type of cable chosen, and the equipment used at each end, such as hubs or other directly-connected devices. You can either choose a particular vendor whose cables and hubs meet your needs, or you can consult the 1394b-2002 standard for detailed cable specifications. Where can I get a detailed description of the DV Standard? When referring to IEEE 1394 devices, "DV" generally indicates a camera that can record standard definition digital video (and audio) on "DV" and/or "miniDV" tapes. The miniDV tape is most common in consumer and "pro-sumer" cameras, and is about the size of a matchbox, while the full-sized "DV" tape is found in professional gear, and is roughly the size of a deck of playing cards. On both kinds of tape, the basic video format and quality are identical, but the larger tape provides extra durability for professional users. There are also a variety of higher quality formats using the same tapes, such as DV50, DV100, DVCPRO, DVCAM, and HDV. In addition to cameras, there are also decks, converter boxes, hard drives, DVD recorders, and computers that can work with DV-format video. The signal encoding, 1394 streaming, 1394
commands, and tape mechanical properties are all defined by standards.
The basic audio/video encoding is defined by ISO/IEC 61834, while the
streaming protocol for this content on 1394 is defined by ISO/IEC 61883,
both of which are available at Another option for cameras on 1394 is the "IIDC" camera specification, sometimes known by its old name "DCAM". This specification provides raw video, in contrast to DV which is compressed. Raw video consumes much more bandwidth on 1394, but is often easier to work with and may provide better signal quality. The IIDC camera specification is available from the 1394 TA. Has the Digital Video copy protect problem now been resolved? Yes - 1394 products such as televisions, AV hard drives, Digital VHS, and Cable set-top boxes are now available with a standard copy protection technology known as DTCP (Digital Transmission Content Protection), often known by its nickname 5C (for the five companies that defined it: Hitachi, Intel, Matsushita, Sony, and Toshiba), which provides a robust, secure transport mechanism that has never been cracked. Developers can license this technology from the DTLA (Digital Transmission Licensing Administrator) at http://www.dtcp.com/ What about protection for content coming into the home or office? The 5C protocols as defined may be used by service providers (cable companies, for example) in conjunction with their own specific content security implementations. Yes - the name "FireWire" was trademarked by Apple Computer before the 1394 standard was published. Years later, the name "i.LINK" was trademarked by Sony. Both names are used widely today, and the 1394 Trade Association has been granted rights to license the use of these trademarks at no cost. Qualified products can also use a compliance logo based on these names, when licensed by the 1394 TA. Where can I obtain a copy of the specification? The 1394-1995, 1394a-2000, and 1394b-2002 specifications are available only from the IEEE, and can be obtained through their web site at http://www.ieee.org. What is the status of 1394a, and what does it achieve? IEEE 1394a is a supplement to the IEEE 1394-1995 standard, which promotes interoperability and performance while maintaining compatibility with existing products. It also clears up some ambiguities and undocumented features in the 1394-1995 version. IEEE 1394a was published in the year 2000 and given the formal name IEEE 1394a-2000. What is 1394b, and when will it be available? IEEE 1394b is a significant enhancement to the basic 1394 specification that enables speed increases to 3.2 Gigabits/sec, supports distances of 100 meters on UTP-5, plastic optical fiber and glass optical fiber, and significantly reduces latency times by using arbitration pipelining. It is fully backwards compatible with the 1394-1995 and 1394a-2000 specifications. 1394b provides the speed and distance necessary to implement a home backbone for AV and Internet data, and is also used directly in computers for high-speed peripherals such as hard disk drives and video cameras. The 1394b standard was published in the year 2002 and given the formal name IEEE 1394b-2002. What kind of bridging work is now underway to enable the use of 1394 in networking applications? The 1394.1 standard was published in 2005, and it defines a bus bridge that can connect two (or more) 1394 busses, allowing the use of greater distances and more than 63 nodes, with improved performance due to the isolation of traffic as appropriate between busses. For Internet Protocol (IP) applications, no bridging is required. IEEE 1394 can directly support IPv4 and IPv6 networking, and can optionally be bridged to other IP networks such as Ethernet and WiFi. How does the 1394 bus compare to USB, SATA, HDMI or Fiber Channel? This depends on your point of view. 1394 has features and capabilities in common with each of these interfaces, but there are also many differences. For example, USB, SATA and Fiber Channel are all computer-type interfaces, used nearly exclusively in a master-slave configuration. In contrast, 1394 is a peer-to-peer interface that works well for computer peripherals, but 1394 is also suitable for an environment with multiple devices that work cooperatively without a central PC for coordination, such as a living-room cluster of audio-video equipment. HDMI is commonly used to deliver a digital signal to a television, but it represents a one-way dead end connection that cannot be used cooperatively like 1394 can. The same video signal, if sent over 1394 instead of HDMI, will consume much less bandwidth, so it is far more practical to record for time-shifting or storage (if copyrights are honored). Is 1394 a good fit for industrial applications? Yes - 1394, especially 1394b, provides numerous benefits suitable for industrial, scientific, and medical applications. The high speed offered by 1394 can provide real time machine control or high-quality video for machine vision and factory automation applications. The long distance offered by 1394b allows many devices in a large factory to be connected, and also allows control equipment (and people) to be located at a safe distance from dangerous equipment or conditions. The optical fiber options in 1394b also provide electrical isolation that can improve safety and reliability, while eliminating electromagnetic emissions that could interfere with equipment or measurements. The Industrial and Instrumentation Working Group within the 1394 TA has developed various specifications to assist with this kind of application. What other applications can 1394 be used for? 1394 is so flexible that it has been widely deployed beyond the computer and consumer electronics markets. As noted above, 1394 cameras and control are used for machine vision, factory automation, and industrial applications. 1394 cables, connectors, and protocols have been specified for automotive use, both for in-vehicle entertainment and for more critical system such as video rear-view mirrors. 1394 has been designed into satellites and advanced military aircraft. 1394 is also used for professional audio and studio applications, where a single 400 megabit cable can carry well over 400 simultaneous channels of CD-quality uncompressed digital audio. Hundreds of models of computer peripherals are available with 1394, including hard disk drives and other storage products, the iPod, web cameras, audio and video breakout boxes, scanners, printers, hubs, and long-haul extenders. Consumer-electronic products such as DV cameras and televisions might not be considered peripherals, but they can also be connected to computers using 1394 to enable many new applications. Where can I find out about 1394 training programs? KnowledgeTek, Inc. (http://www.knowledgetek.com) is based in Broomfield, Colorado (telephone 303-465-1800) and offers courses at different locations. Dap Technology (http://www.daptechnology.com) offers half-day and full-day workshops focused on 1394b and Dap's test tools. Is there a basic list of 1394-based equipment and products now available? The 1394 Trade Association compiles a product book and maintains a web listing of products that use 1394. Visit the website or contact the TA for a copy. Are there any books available about 1394? MindShare (http://www.mindshare.com) publishes a book on the 1394 architecture called FireWire System Architecture.
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