ALLIED Vision Technologies Guppy PRO F-503 - Manual (Page 29)

FireWire
Guppy PRO Technical Manual V4.0.0
28
Bus runs at 800 Mbit/s for all devices. Data from Marlin’s port is up-converted
from 400 Mbit/s to 800 Mbit/s by data doubling (padding), still needing 32%
of the cycle slot time. This doubles the bandwidth requirement for this port,
as if the camera were running at 60 fps. Total consumption is thus

2560+ 2560 = 5120 bytes per cycle.
Image transfer via 1394a and 1394b
Technical detail 1394a 1394b
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
~ 1000q @ 400 Mbit/s
8192 bytes per cycle
~ 2000q @ 800 Mbit/s
(@1 GHz clock rate)
For further detail read Chapter Frame rates on page 184.
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 asynchro-
nous performance of widespread
network (round trip delay),
reducing efficiency
No gaps needed, BOSS mode for
parallel arbitration
Table 3: Technical detail comparison: 1394a and 1394b
Note

The bandwidth values refer to the fact:
1 MByte = 1024 kByte