Pike Technical Manual
V5.2.0
39
FireWire
IIDC V1.31 camera control standards
Along with 1394b-, the IIDC V1.31 standard arrived in January 2004, evolving
the industry standards for digital imaging communications to include
I/O and RS232 handling, and adding further formats. The increased bandwidths
enable transmitting high-resolution images to the PC’s memory at high frame
rates.
Compatibility between 1394a and 1394b
Compatibility example
It’s possible to run a 1394a and a 1394b camera on the 1394b bus.
You can e.g. run a Pike F-032B and a Marlin F-033B on the same bus:
•
Pike F-032B @ S800 and 120 fps (5120 bytes per cycle, 64% of the cycle
slot)
•
Marlin F-033B @ S400 and 30 fps (1280 bytes, 32% of the cycle slot)
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 5120 + 2560 =
7680 bytes per cycle.
1394a camera connected to 1394b bus
The cable explains dual compatibility: This cable
serves to connect an IEEE 1394a camera with its
six-
pin
connector to a bilingual port (a port which can
talk in a- or b-language) of a 1394b bus.
In this case, the b-bus communicates in
a-language and a-speed with the camera achieving
a-performance
1394b camera connected to 1394a bus
The cable explains dual compatibility: In this case,
the cable connects an IEEE 1394b camera with its
nine-pin
connector to a 1394a port.
In this case, the b-camera communicates in
a-language with the camera achieving
a-performance
Figure 4: 1394a and 1394b cameras and compatibility
1394b port
1394a camera
1394a port
1394b camera
