Instruction manual

IQ-PIP-USP3/CN
page 34 Reference Manual
The Conductor regulates the CobraNet digital audio traffic on the CobraNet network. Each
transmitter is given a “permission” to transmit in a given time-slot within the Conductor
controlled isochronous cycle-time. The time-slot is determined by the assigned bundle pri-
ority. Higher bundle priorities receive lower-numbered positions and are transmitted first.
The “Receiver Count” monitor indicates how many devices are recieving the digital audio
bundle. The “Active” indicator indicates whether the particular Bundle is being actively
transmitted onto the network.
5.3.4 Bundles and Audio Channels
All audio channels are packaged into groups called Bundles (formerly called Network
Channels) for transmission over the Ethernet network. Each CobraNet device has the ability
to send and receive a fixed number of Bundles. The Bundle number tells the CobraNet con-
ductor which specific CobraNet device is trying to communicate with which other CobraNet
device(s) over the network. A given Bundle may have only one transmitter that places it
onto the network. Unicast Bundles may have only a single receiver. Multicast Bundles may
have multiple receivers.
Bundles from 1 to 255 are designated as “multi-cast” Bundles. This means that they are
transmitted to multiple receivers. This type is most used on “repeater” networks limited to
64 channels.
Bundles from 256 to 65,279 are “uni-cast”. This means that they are transmitted to one and
only one receiver. This type is most used on “switched” networks requiring more than 64
channels.
A Bundle can carry up to 8 audio channels (see the block diagram in Section ??). The usual
assignment is 8 channels at 20 bits. Using less audio channels is possible but maximum
size bundles are suggested for most efficient utilization of network bandwidth. If 24-bit data
is desired, then only 7 audio channels can be loaded into a single Bundle.
5.3.5 Repeater Networks
CobraNet can operate on “repeater” networks and more complex “switched” networks.
Repeater networks use low-cost Ethernet hubs.* On this type of an Ethernet network, all
packets are broadcast to all connected nodes. CobraNet multi-cast and uni-cast Bundles
can be assigned but because of the simpler repeater-type hubs, even uni-cast transmis-
sions are broadcast to all nodes. Therefore, a maximum of 8 full-loaded Bundles (64 audio
channels) are allowed on the entire network. More Bundles may be allowed if they are
loaded with less than the full eight audio channels. There is no limit to the number of active
receivers on a repeater network. Generally, a repeater based CobraNetnetwork must be ded-
icated to CobraNet traffic only to guarantee reliable transmission of audio packets.
*See Tested Ethernet Products on the Peak Audio website for a list of recommended Ether-
net repeaters.