ALLIED Vision Technologies Guppy PRO F-503 - Manual (Page 27)

FireWire
Guppy PRO Technical Manual V4.0.0
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FireWire also supports multiple hosts per bus. FireWire requires only a cable
with the correct number of pins on either end (normally 6 or 9). It is
designed to support plug-and-play and hot swapping. It can supply up to
45 W of power per port at 30 V, allowing high consumption devices to oper-
ate without a separate power cord.
Capabilities of 1394a (FireWire 400)
FireWire 400 (S400) is able to transfer data between devices at 100, 200 or
400 MBit/s data rates. Although USB 2.0 claims to be capable of higher
speeds (480 Mbit/s), FireWire is, in practice, not slower than USB 2.0.
The 1394a capabilities in detail:
• 400 Mbit/s
• Hot-pluggable devices
• Peer-to-peer communications
• Direct Memory Access (DMA) to host memory
• Guaranteed bandwidth
• Multiple devices (up to 45 W) powered via FireWire bus
IIDC V1.3 camera control standards
IIDC V1.3 released a set of camera control standards via 1394a which estab-
lished a common communications protocol on which most current FireWire
cameras are based.
In addition to common standards shared across manufacturers, a special
Format_7 mode also provided a means by which a manufacturer could offer
special features (smart features), such as:
• higher resolutions
• higher frame rates
• diverse color modes
as extensions (advanced registers) to the prescribed common set.
Capabilities of 1394b (FireWire 800)
FireWire 800 (S800) was introduced commercially by Apple in 2003 and has
a 9-pin FireWire 800 connector (see details in Hardware Installation Guide
and in Chapter
IEEE 1394b port pin assignment on page 70). This newer
1394b specification allows a transfer rate of 800 MBit/s with backward com-
patibilities to the slower rates and 6-pin connectors of FireWire 400.
Caution

While supplying such an amount of bus power is clearly a
beneficial feature, it is very important not to exceed the
inrush current of 18 mJoule in 3 ms.
Higher inrush current may damage the Phy chip of the
camera and/or the Phy chip in your PC.