Pike
Technical
Manual
V5.2.3
39
FireWire
FireWire
Image transfer via IEEE1394a and IEEE1394b
IEEE1394b bandwidths
According
to
the
IEEE1394b
specification
on
isochronous
transfer,
the
largest
recommended
data
payload
size
is
8192
bytes
per
125
µs
cycle
at
a
bandwidth
of
800
Mbit/s.
Technical detail
IEEE1394a
IEEE1394b
Transmission
mode
Half
duplex
(both
pairs
needed)
400
Mbit/s
data
rate
aka:
a-mode,
data/strobe
(D/S)
mode,
legacy
mode
Full
duplex
(one
pair
needed)
1
Gbit/s
signaling
rate,
800
Mbit/s
data
rate
10b/8b
coding
(Ethernet),
aka:
b-
mode
(beta
mode)
Devices
Up
to
63
devices
per
network
Number
of
cameras
Up
to
16
cameras
per
network
Number
of
DMAs
4
to
8
DMAs
(parallel)
cameras
/
bus
Real-time
capability
Image
has
real-time
priority
Available
bandwidth
acc.
IIDC
(per
cycle
125
µs)
4096
bytes
per
cycle
~
1000
quadlets
@
400
Mbit/s
8192
bytes
per
cycle
~
2000
quadlets
@
800
Mbit/s
(@1
GHz
clock
rate)
For
more
information,
see
Max.
image
bandwidth
31.25
MByte/s
62.5
MByte/s
Max.
total
bandwidth
~45
MByte/s
~85
MByte/s
Number
of
busses
Multiple
busses
per
PC
limit:
PCI
bus
Multiple
busses
per
PC
limit:
PCI
(Express)
bus
CPU
load
Almost
none
for
DMA
image
transfer
Gaps
Gaps
negatively
affect
asynchronous
performance
of
widespread
network
(round
trip
delay),
reducing
efficiency
No
gaps
needed,
BOSS
mode
for
parallel
arbitration
Table 4: Technical detail comparison: IEEE1394a and IEEE1394b
Note
The
bandwidth
values
refer
to
1
MByte
=
1024
KB