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- Question on Firewire Cables
June 22, 2006, 9:51 am
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Re: Question on Firewire Cables
The difference is the two bus power pins. Bus power (from
a 6 pin interface) allows the computer to provide the
operating power to the peripheral.
But one advantage of peripherals that don't have provision
for bus power (like a DV camera), is that there is less
chance of something going wrong, if the two bus power pins
are not present. (Here is a nice page with pinouts...)
If you look at the six pin connector, two pins are longer
and make contact before, the other four pins. I guess that
means the bus power pins VP/VG make connections first, and then
the TPA+/- data pair, and the TPB+/- data pair. On the four
pin connector, there are no bus power pins, and the data pins
are all safe low voltage signals.
The one web page that attempted to address Firewire failures,
If more Firewire devices were connected via just four pins,
I can see a good deal of the problems discussed on that web
page, as being cured.
I follow the hot plug cautions on this page, and do not
hot plug Firewire (while I do hot plug USB). For Firewire,
I wire everything up, power up the peripheral (in my case
a Firewire disk enclosure), then power up the computer.
I reverse that order after I'm done. My main reason for
being careful, is I use a 6 pin to 6 pin cable, being
too cheap to arrange anything else :-)