Cable Power - Yamaha mLAN Manual Book

Technical Explanations

6. Cable Power

Nodes with multiple IEEE 1394 connectors have the important role of relaying and transmitting
data between multiple connected nodes. In order for data to be transferred from one node to
another, each node between these nodes must relay the data accurately. A small amount of elec-
trical power is required for the relay functionality to operate. So that its relay functionality will
continue to operate even if the power of a device is turned off, there must be a means of supply-
ing power from other nodes. Thus, standard IEEE 1394 cables use a four-pin configuration; four
pins for data and control signals, or a six-pin configuration; four pins for data and control signals
and two pins for electrical power.
mLAN feature
Although DV cables that omit the power lines do exist, mLAN products use six-pin cables.
Figure 8: Cross-section of a six-pin cable
Two sets
of twisted
pair signal lines
Since the six-pin cables are able to transmit power, power can be distributed between nodes of
the network. Nodes can be classified by how they handle power.
By power supply
A. Nodes that are able to supply power to another node via the cable. These are called
"power nodes."
B. Nodes that are not able to supply power.
16
Power supply cable
(8–40 V DC, maximum current 1.5 A)
ON
OFF
Power can be supplied.
ON
OFF
Power cannot be supplied.
Signal line shield
Number of
connector pins
P
P
P
P
Supported
speed
6 400Mbps
P : Electric power
: Can be supplied/relayed
: Cannot be supplied/relayed