Misplaced Pages

IEEE 1394

Article snapshot taken from Wikipedia with creative commons attribution-sharealike license. Give it a read and then ask your questions in the chat. We can research this topic together.

In telecommunications , an interface standard is a standard that describes one or more functional characteristics (such as code conversion , line assignments, or protocol compliance) or physical characteristics (such as electrical, mechanical, or optical characteristics) necessary to allow the exchange of information between two or more (usually different) systems or pieces of equipment. Communications protocols are an example.

#733266

65-532: IEEE 1394 is an interface standard for a serial bus for high-speed communications and isochronous real-time data transfer. It was developed in the late 1980s and early 1990s by Apple in cooperation with a number of companies, primarily Sony and Panasonic . It is most commonly known by the name FireWire (Apple), though other brand names exist such as i.LINK (Sony), and Lynx ( Texas Instruments ). The copper cable used in its most common implementation can be up to 4.5 metres (15 ft) long. Power and data

130-665: A CPU , a GPU , a FPGA or a combination of these. Deep learning training and inference impose higher processing performance requirements. Multiple stages of processing are generally used in a sequence that ends up as a desired result. A typical sequence might start with tools such as filters which modify the image, followed by extraction of objects, then extraction (e.g. measurements, reading of codes) of data from those objects, followed by communicating that data, or comparing it against target values to create and communicate "pass/fail" results. Machine vision image processing methods include; A common output from automatic inspection systems

195-438: A systems engineering discipline can be considered distinct from computer vision , a form of computer science . It attempts to integrate existing technologies in new ways and apply them to solve real world problems. The term is the prevalent one for these functions in industrial automation environments but is also used for these functions in other environment vehicle guidance. The overall machine vision process includes planning

260-572: A FireWire hub is used) computer networks . Specifically, RFC 2734 specifies how to run IPv4 over the FireWire interface, and RFC 3146 specifies how to run IPv6 . Mac OS X, Linux , and FreeBSD include support for networking over FireWire. Windows 95 , Windows 98 , Windows Me , Windows XP and Windows Server 2003 include native support for IEEE 1394 networking. Windows 2000 does not have native support but may work with third party drivers. A network can be set up between two computers using

325-467: A Sony camera being the only notable user. A project named IEEE P1394d was formed by the IEEE on March 9, 2009 to add single-mode fiber as an additional transport medium to FireWire. The project was withdrawn in 2013. Other future iterations of FireWire were expected to increase speed to 6.4 Gbit/s and additional connectors such as the small multimedia interface. Full support for IEEE 1394a and 1394b

390-476: A build-to-order option on some models since 1997), and most Apple Macintosh computers manufactured in the years 2000 through 2011 included FireWire ports. However, in February 2011 Apple introduced the first commercially available computer with Thunderbolt . Apple released its last computers with FireWire in 2012. By 2014, Thunderbolt had become a standard feature across Apple's entire line of computers (later with

455-445: A certain percentage to isochronous data and the rest to asynchronous data. In IEEE 1394, 80% of the bus is reserved for isochronous cycles, leaving asynchronous data with a minimum of 20% of the bus. FireWire uses Data/Strobe encoding (D/S encoding). In D/S encoding, two non-return-to-zero (NRZ) signals are used to transmit the data with high reliability. The NRZ signal sent is fed with the clock signal through an XOR gate , creating

520-519: A device can pull about 7 to 8 watts from the port; however, the voltage varies significantly from different devices. Voltage is specified as unregulated and should nominally be about 25 volts (range 24 to 30). Apple's implementation on laptops is typically related to battery power and can be as low as 9 V. An amendment, IEEE 1394a, was released in 2000, which clarified and improved the original specification. It added support for asynchronous streaming , quicker bus reconfiguration, packet concatenation , and

585-512: A framegrabber) to a computer via FireWire , USB or Gigabit Ethernet interfaces. While conventional (2D visible light) imaging is most commonly used in MV, alternatives include multispectral imaging , hyperspectral imaging , imaging various infrared bands, line scan imaging, 3D imaging of surfaces and X-ray imaging. Key differentiations within MV 2D visible light imaging are monochromatic vs. color, frame rate , resolution, and whether or not

650-416: A major technical improvement, namely new port specification that provides 800 Mbit/s over the same 8P8C (Ethernet) connectors with Category 5e cable , which is specified in IEEE 802.3 clause 40 ( gigabit Ethernet over copper twisted pair ) along with a corresponding automatic negotiation that allows the same port to connect to either IEEE Std 1394 or IEEE 802.3 ( Ethernet ) devices. In December 2007,

715-642: A military and aerospace databus network in those vehicles. AS5643 is utilized by several large programs, including the F-35 Lightning II , the X-47B UCAV aircraft, AGM-154 weapon and JPSS-1 polar satellite for NOAA. AS5643 combines existing 1394-2008 features like looped topology with additional features like transformer isolation and time synchronization, to create deterministic double and triple fault-tolerant data bus networks. FireWire can be used for ad hoc (terminals only, no routers except where

SECTION 10

#1732787082734

780-449: A number of PC desktops, and other small FireWire devices. The 4-conductor connector is fully data-compatible with 6-conductor alpha interfaces but lacks power connectors. IEEE 1394b-2002 introduced FireWire 800 (Apple's name for the 9-conductor S800 bilingual version of the IEEE 1394b standard). This specification added a new encoding scheme termed beta mode which allowed compliant devices to operate at 786.432 Mbit/s full-duplex . It

845-556: A power-saving suspend mode . IEEE 1394a offers a couple of advantages over the original IEEE 1394–1995. 1394a is capable of arbitration accelerations, allowing the bus to accelerate arbitration cycles to improve efficiency. It also allows for arbitrated short bus reset, in which a node can be added or dropped without causing a big drop in isochronous transmission. 1394a also standardized the 4-conductor alpha connector developed by Sony and trademarked as i.LINK , already widely in use on consumer devices such as camcorders, most PC laptops,

910-488: A single standard FireWire cable, or by multiple computers through use of a hub. This is similar to Ethernet networks with the major differences being transfer speed, conductor length, and the fact that standard FireWire cables can be used for point-to-point communication. On December 4, 2004, Microsoft announced that it would discontinue support for IP networking over the FireWire interface in all future versions of Microsoft Windows . Consequently, support for this feature

975-465: A solution. This section describes the technical process that occurs during the operation of the solution. The first step in the automatic inspection sequence of operation is acquisition of an image , typically using cameras, lenses, and lighting that has been designed to provide the differentiation required by subsequent processing. MV software packages and programs developed in them then employ various digital image processing techniques to extract

1040-407: A strobe signal. This strobe is then put through another XOR gate along with the data signal to reconstruct the clock. This in turn acts as the bus's phase-locked loop for synchronization purposes. The process of the bus deciding which node gets to transmit data at what time is known as arbitration . Each arbitration round lasts about 125 microseconds. During the round, the root node (device nearest

1105-523: A superseding standard, IEEE 1394-2008 . The features individually added give a good history on the development path. The original release of IEEE 1394-1995 specified what is now known as FireWire 400. It can transfer data between devices at 100, 200, or 400  Mbit/s half-duplex data rates (the actual transfer rates are 98.304, 196.608, and 393.216 Mbit/s, i.e., 12.288, 24.576 and 49.152 MB/s respectively). These different transfer modes are commonly referred to as S100, S200, and S400. Cable length

1170-671: A way that meets the requirements of industrial automation and similar application areas. The term is also used in a broader sense by trade shows and trade groups such as the Automated Imaging Association and the European Machine Vision Association. This broader definition also encompasses products and applications most often associated with image processing. The primary uses for machine vision are automatic inspection and industrial robot /process guidance. In more recent times

1235-549: Is Apple's name for the IEEE 1394 High Speed Serial Bus. Its development was initiated by Apple in 1986, and developed by the IEEE P1394 Working Group, largely driven by contributions from Sony (102 patents), Apple (58 patents), Panasonic (46 patents), and Philips (43 patents), in addition to contributions made by engineers from LG Electronics , Toshiba , Hitachi , Canon , INMOS /SGS Thomson (now STMicroelectronics ), and Texas Instruments . IEEE 1394

1300-510: Is a serial bus architecture for high-speed data transfer, serial meaning that information is transferred one bit at a time. Parallel buses utilize a number of different physical connections, and as such are usually more costly and typically heavier. IEEE 1394 fully supports both isochronous and asynchronous applications. Apple intended FireWire to be a serial replacement for the parallel SCSI bus, while providing connectivity for digital audio and video equipment. Apple's development began in

1365-478: Is absent from Windows Vista and later Windows releases. Microsoft rewrote their 1394 driver in Windows 7 but networking support for FireWire is not present. Unibrain offers free FireWire networking drivers for Windows called ubCore, which support Windows Vista and later versions. Interface standard An interface standard may include operational characteristics and acceptable levels of performance. In

SECTION 20

#1732787082734

1430-450: Is also used to guide motion that is simpler than robots, such as a 1 or 2 axis motion controller. The overall process includes planning the details of the requirements and project, and then creating a solution. This section describes the technical process that occurs during the operation of the solution. Many of the process steps are the same as with automatic inspection except with a focus on providing position and orientation information as

1495-732: Is available for Microsoft Windows , FreeBSD , Linux , Apple Mac OS 8.6 through macOS 14 Sonoma and NetBSD . In Windows XP, a degradation in performance of 1394 devices may have occurred with installation of Service Pack 2. This was resolved in Hotfix 885222 and in SP3 . Some FireWire hardware manufacturers also provide custom device drivers that replace the Microsoft OHCI host adapter driver stack, enabling S800-capable devices to run at full 800 Mbit/s transfer rates on older versions of Windows (XP SP2 w/o Hotfix 885222) and Windows Vista. At

1560-402: Is backwards compatible with the slower rates and 6-conductor alpha connectors of FireWire 400. However, while the IEEE 1394a and IEEE 1394b standards are compatible, FireWire 800's connector, referred to as a beta connector, is different from FireWire 400's alpha connectors, making legacy cables incompatible. A bilingual cable allows the connection of older devices to the newer port. In 2003, Apple

1625-462: Is carried over this cable, allowing devices with moderate power requirements to operate without a separate power supply. FireWire is also available in Cat 5 and optical fiber versions. The 1394 interface is comparable to USB . USB was developed subsequently and gained much greater market share. USB requires a host controller whereas IEEE 1394 is cooperatively managed by the connected devices. FireWire

1690-442: Is designed to support plug and play and hot swapping . The copper cable it uses in its most common implementation can be up to 4.5 metres (15 ft) long and is more flexible than most parallel SCSI cables. In its six-conductor or nine-conductor variations, it can supply up to 45 watts of power per port at up to 30 volts, allowing moderate-consumption devices to operate without a separate power supply. FireWire devices implement

1755-511: Is generally called a smart camera or smart sensor. Inclusion of the full processing function into the same enclosure as the camera is often referred to as embedded processing. When separated, the connection may be made to specialized intermediate hardware, a custom processing appliance, or a frame grabber within a computer using either an analog or standardized digital interface ( Camera Link , CoaXPress ). MV implementations also use digital cameras capable of direct connections (without

1820-538: Is limited to 4.5 metres (14.8 ft), although up to 16 cables can be daisy chained using active repeaters, e.g. external hubs or the internal hubs that are often present in FireWire equipment. The S400 standard limits any configuration's maximum cable length to 72 metres (236 ft). The 6-conductor connector is commonly found on desktop computers and can supply the connected device with power. The 6-conductor powered connector, now referred to as an alpha connector, adds power output to support external devices. Typically

1885-542: Is pass/fail decisions. These decisions may in turn trigger mechanisms that reject failed items or sound an alarm. Other common outputs include object position and orientation information for robot guidance systems. Additionally, output types include numerical measurement data, data read from codes and characters, counts and classification of objects, displays of the process or results, stored images, alarms from automated space monitoring MV systems, and process control signals. This also includes user interfaces, interfaces for

1950-464: Is practically the only term used for these functions in industrial automation applications; the term is less universal for these functions in other environments such as security and vehicle guidance. Machine vision as a systems engineering discipline can be considered distinct from computer vision , a form of basic computer science ; machine vision attempts to integrate existing technologies in new ways and apply them to solve real world problems in

2015-415: Is said to require use of 261 issued international patents held by ten corporations. Use of these patents requires licensing; use without license generally constitutes patent infringement . Companies holding IEEE 1394 IP formed a patent pool with MPEG LA, LLC as the license administrator, to whom they licensed patents. MPEG LA sublicenses these patents to providers of equipment implementing IEEE 1394. Under

IEEE 1394 - Misplaced Pages Continue

2080-493: Is the library source for all 1394 documentation and standards available. FireWire can connect up to 63 peripherals in a tree or daisy-chain topology (as opposed to Parallel SCSI's electrical bus topology). It allows peer-to-peer device communication — such as communication between a scanner and a printer — to take place without using system memory or the CPU . FireWire also supports multiple host controllers per bus. It

2145-480: Is used in special cases involving unique features present in both views of a pair of cameras. Other 3D methods used for machine vision are time of flight and grid based. One method is grid array based systems using pseudorandom structured light system as employed by the Microsoft Kinect system circa 2012. After an image is acquired, it is processed. Central processing functions are generally done by

2210-406: The "physics" phase of a machine vision automatic inspection solution to create reliable simple differentiation of defects. An example of "simple" differentiation is that the defects are dark and the good parts of the product are light. A common reason why some applications were not doable was when it was impossible to achieve the "simple"; deep learning removes this requirement, in essence "seeing"

2275-887: The 1394 Trade Association announced that products would be available before the end of 2008 using the S1600 and S3200 modes that, for the most part, had already been defined in 1394b and were further clarified in IEEE Std. 1394–2008. The 1.572864 Gbit/s and 3.145728 Gbit/s devices use the same 9-conductor beta connectors as the existing FireWire 800 and are fully compatible with existing S400 and S800 devices. It competes with USB 3.0 . S1600 (Symwave) and S3200 (Dap Technology) development units have been made, however because of FPGA technology DapTechnology targeted S1600 implementations first with S3200 not becoming commercially available until 2012. Steve Jobs declared FireWire dead in 2008. As of 2012, there were few S1600 devices released, with

2340-529: The FCC issued an order that permitted set-top boxes to include IP-based interfaces in place of FireWire. While both technologies provide similar end results, there are fundamental differences between USB and FireWire. USB requires the presence of a host controller, typically a PC, which connects point to point with the USB device. This allows for simpler (and lower-cost) peripherals, at the cost of lowered functionality of

2405-458: The ISO/IEC 13213 configuration ROM model for device configuration and identification, to provide plug-and-play capability. All FireWire devices are identified by an IEEE EUI-64 unique identifier in addition to well-known codes indicating the type of device and the protocols it supports. FireWire devices are organized at the bus in a tree topology. Each device has a unique self-ID. One of

2470-623: The actual 1394 Patent Portfolio License upon request to MPEG LA. MPEG LA does not provide assurance of protection to licensees beyond its own patents. At least one formerly licensed patent is known to have been removed from the pool, and other hardware patents exist that reference IEEE 1394. The 1394 High Performance Serial Bus Trade Association (the 1394 TA ) was formed to aid the marketing of IEEE 1394. Its bylaws prohibit dealing with intellectual property issues. The 1394 Trade Association operates on an individual no cost membership basis to further enhancements to 1394 standards. The Trade Association also

2535-502: The bus network, whereas, until USB 3.0, USB featured only one. This means that FireWire can have communication in both directions at the same time (full-duplex), whereas USB communication prior to 3.0 can only occur in one direction at any one time (half-duplex). While USB 2.0 expanded into the fully backwards-compatible USB 3.0 and 3.1 (using the same main connector type), FireWire used a different connector between 400 and 800 implementations. IDB-1394 Customer Convenience Port (CCP)

2600-517: The bus. Intelligent hubs are required to connect multiple USB devices to a single USB host controller. By contrast, FireWire is essentially a peer-to-peer network (where any device may serve as the host or client), allowing multiple devices to be connected on one bus. The FireWire host interface supports DMA and memory-mapped devices, allowing data transfers to happen without loading the host CPU with interrupts and buffer-copy operations. Additionally, FireWire features two data buses for each segment of

2665-443: The cables, while 1394b added a data encoding scheme called 8b/10b referred to as beta mode . Beta mode is based on 8b/10b (from Gigabit Ethernet , also used for many other protocols). 8b/10b encoding involves expanding an 8-bit data word into 10 bits, with the extra bits after the 5th and 8th data bits. The partitioned data is sent through a Running Disparity calculator function. The Running Disparity calculator attempts to keep

IEEE 1394 - Misplaced Pages Continue

2730-419: The coding scheme is to support the arbitration for bus access and general bus control. This is possible due to the surplus symbols afforded by the 8b/10b expansion. (While 8-bit symbols can encode a maximum of 256 values, 10-bit symbols permit the encoding of up to 1024.) Symbols invalid for the current state of the receiving PHY indicate data errors. IEEE 1394c-2006 was published on June 8, 2007. It provided

2795-412: The details of the requirements and project, and then creating a solution. During run-time, the process starts with imaging, followed by automated analysis of the image and extraction of the required information. Definitions of the term "Machine vision" vary, but all include the technology and methods used to extract information from an image on an automated basis, as opposed to image processing , where

2860-457: The devices. FireWire is capable of both asynchronous and isochronous transfer methods at once. Isochronous data transfers are transfers for devices that require continuous, guaranteed bandwidth. In an aircraft, for instance, isochronous devices include control of the rudder , mouse operations and data from pressure sensors outside the aircraft. All these elements require constant, uninterrupted bandwidth. To support both elements, FireWire dedicates

2925-537: The exception of the 12-inch MacBook introduced in 2015, which featured only a sole USB-C port), effectively becoming the spiritual successor to FireWire in the Apple ecosystem. Apple's last products with FireWire, the Thunderbolt Display and 2012 13-inch MacBook Pro , were discontinued in 2016. Apple previously sold a Thunderbolt to FireWire Adapter, which provided one FireWire 800 port. A separate adapter

2990-422: The imaging process is simultaneous over the entire image, making it suitable for moving processes. Though the vast majority of machine vision applications are solved using two-dimensional imaging, machine vision applications utilizing 3D imaging are a growing niche within the industry. The most commonly used method for 3D imaging is scanning based triangulation which utilizes motion of the product or image during

3055-427: The imaging process. A laser is projected onto the surfaces of an object. In machine vision this is accomplished with a scanning motion, either by moving the workpiece, or by moving the camera & laser imaging system. The line is viewed by a camera from a different angle; the deviation of the line represents shape variations. Lines from multiple scans are assembled into a depth map or point cloud. Stereoscopic vision

3120-461: The integration of multi-component systems and automated data interchange. The term deep learning has variable meanings, most of which can be applied to techniques used in machine vision for over 20 years. However the usage of the term in "machine vision" began in the later 2010s with the advent of the capability to successfully apply such techniques to entire images in the industrial machine vision space. Conventional machine vision usually requires

3185-533: The known interface types are: This article related to telecommunications is a stub . You can help Misplaced Pages by expanding it . Machine vision Machine vision is the technology and methods used to provide imaging -based automatic inspection and analysis for such applications as automatic inspection, process control , and robot guidance, usually in industry. Machine vision refers to many technologies, software and hardware products, integrated systems, actions, methods and expertise. Machine vision as

3250-644: The late 1980s, later presented to the IEEE, and was completed in January 1995. In 2007, IEEE 1394 was a composite of four documents: the original IEEE Std. 1394–1995, the IEEE Std. 1394a-2000 amendment, the IEEE Std. 1394b-2002 amendment, and the IEEE Std. 1394c-2006 amendment. On June 12, 2008, all these amendments as well as errata and some technical updates were incorporated into a superseding standard, IEEE Std. 1394–2008. Apple first included onboard FireWire in some of its 1999 Macintosh models (though it had been

3315-507: The military community, interface standards permit command and control functions to be performed using communication and computer systems. There are many interface standards between analog telephone central office equipment and customer-premises equipment . Single voice paths generally include analog audio connections, either a two-wire circuit or four-wire circuit plus signaling paths to indicate call progress and status information, such as ringing, answer supervision , etc. Some of

SECTION 50

#1732787082734

3380-413: The nodes is elected root node and always has the highest ID. The self-IDs are assigned during the self-ID process, which happens after each bus resets. The order in which the self-IDs are assigned is equivalent to traversing the tree depth-first , post-order. FireWire is capable of safely operating critical systems due to the way multiple devices interact with the bus and how the bus allocates bandwidth to

3445-457: The number of 1s transmitted equal to 0s, thereby assuring a DC-balanced signal. Then, the different partitions are sent through a 5b/6b encoder for the 5-bit partition and a 3b/4b encoder for the 3-bit partition. This gives the packet the ability to have at least two 1s, ensuring synchronization of the PLL at the receiving end to the correct bit boundaries for reliable transfer. An additional function of

3510-405: The object more as a human does, making it now possible to accomplish those automatic applications. The system learns from a large amount of images during a training phase and then executes the inspection during run-time use which is called "inference". Machine vision commonly provides location and orientation information to a robot to allow the robot to properly grasp the product. This capability

3575-526: The output is another image. The information extracted can be a simple good-part/bad-part signal, or more a complex set of data such as the identity, position and orientation of each object in an image. The information can be used for such applications as automatic inspection and robot and process guidance in industry, for security monitoring and vehicle guidance. This field encompasses a large number of technologies, software and hardware products, integrated systems, actions, methods and expertise. Machine vision

3640-399: The processor) sends a cycle start packet. All nodes requiring data transfer respond, with the closest node winning. After the node is finished, the remaining nodes take turns in order. This repeats until all the devices have used their portion of the 125 microseconds, with isochronous transfers having priority. The previous standards and its three published amendments are now incorporated into

3705-399: The required information, and often make decisions (such as pass/fail) based on the extracted information. The components of an automatic inspection system usually include lighting, a camera or other imager, a processor, software, and output devices. The imaging device (e.g. camera) can either be separate from the main image processing unit or combined with it in which case the combination

3770-401: The terms computer vision and machine vision have converged to a greater degree. See glossary of machine vision . The primary uses for machine vision are imaging-based automatic inspection and sorting and robot guidance.; in this section the former is abbreviated as "automatic inspection". The overall process includes planning the details of the requirements and project, and then creating

3835-434: The time of its release, Microsoft Windows Vista supported only 1394a, with assurances that 1394b support would come in the next service pack. Service Pack 1 for Microsoft Windows Vista has since been released, however the addition of 1394b support is not mentioned anywhere in the release documentation. The 1394 bus driver was rewritten for Windows 7 to provide support for higher speeds and alternative media. In Linux, support

3900-436: The typical patent pool license, a royalty of US$ 0.25 per unit is payable by the manufacturer upon the manufacture of each 1394 finished product; no royalties are payable by users. The last of the patents, MY 120654 by Sony, expired on November 30, 2020. As of November 30, 2020, the following are patent holders of the IEEE 1394 standard, as listed in the patent pool managed by MPEG LA . A person or company may review

3965-454: Was also popular in industrial systems for machine vision and professional audio systems. Many users preferred it over the more common USB 2.0 for its then greater effective speed and power distribution capabilities. Benchmarks show that the sustained data transfer rates are higher for FireWire than for USB 2.0, but lower than USB 3.0 . Results are marked on Apple Mac OS X but more varied on Microsoft Windows . Implementation of IEEE 1394

SECTION 60

#1732787082734

4030-693: Was originally provided by libraw1394 making direct communication between user space and IEEE 1394 buses. Subsequently, a new kernel driver stack, nicknamed JuJu, has been implemented. Under FCC Code 47 CFR 76.640 section 4, subsections 1 and 2, Cable TV providers (in the US, with digital systems) must, upon request of a customer, have provided a high-definition capable cable box with a functional FireWire interface. This applied only to customers leasing high-definition capable cable boxes from their cable provider after April 1, 2004. The interface can be used to display or record Cable TV, including HDTV programming. In June 2010,

4095-535: Was required to use it with Thunderbolt 3. Sony's implementation of the system, i.LINK , used a smaller connector with only four signal conductors, omitting the two conductors that provide power for devices in favor of a separate power connector. This style was later added into the 1394a amendment. This port is sometimes labeled S100 or S400 to indicate speed in Mbit/s. The system was commonly used to connect data storage devices and DV (digital video) cameras, but

4160-625: Was the automotive version of the 1394 standard. IEEE 1394 was the High-Definition Audio-Video Network Alliance (HANA) standard connection interface for A/V (audio/visual) component communication and control. HANA was dissolved in September 2009 and the 1394 Trade Association assumed control of all HANA-generated intellectual property. SAE Aerospace standard AS5643 originally released in 2004 and reaffirmed in 2013 establishes IEEE-1394 standards as

4225-558: Was the first to introduce commercial products with the new connector, including a new model of the Power Mac G4 and a 17" PowerBook G4 . The full IEEE 1394b specification supports data rates up to 3200 Mbit/s (i.e., 400 MB/s) over beta-mode or optical connections up to 100 metres (330 ft) in length. Standard category 5e cable supports 100 metres (330 ft) at S100. The original 1394 and 1394a standards used data/strobe (D/S) encoding , now known as alpha mode , with

#733266