|
Various Firewire Cables
|
|
Nodes with multiple Firewire 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 electrical 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 supplying power from other nodes.
Thus, standard Firewire 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.
Cross-section of a six-pin-IEEE 1394 cable
Although DV cables that omit the power lines do exist, mLAN products use six- pin cables.
|
|
Classification of the nodes in order of power supply
|
|
Nodes can be classified by how they handle power.
- 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.
- C - Nodes that take no power at all from the cable. When their power is turned off, they will also cease functioning as bus relays.
- D - Nodes that can obtain power from the cable and function as bus relays.
- E - Nodes that can obtain power from the cable and perform all of their own functions (low power consumption portable devices etc.).
For the purpose of power, a node will have a combination of functionality from A or B and C, D or E.
For the current mLAN devices, this will generally be [B] and [c]. In other words, a system consisting solely of mLAN devices will function as a single system only if the power of all devices (nodes) is turned on.
|