What Networks Are Supported; Packets, Bundles & Isochronous Cycles - Yamaha ACU16-C Manual

1 CobraNet
W
P
Beat
packet
An isochronous cycle
CobraNet—the Technical Stuff
hat Networks are Supported?
CobraNet runs on industry-standard 100Base-T Ethernet networks (100 Mbps). It does not
support 10Base-T (10 Mbps). CobraNet can be used with standard off-the-shelf 100Base-T
Ethernet networking equipment, including switches, media converters, CAT5 cables, and so
on. 100Base-T Ethernet equipment is readily available and inexpensive.
ackets, Bundles & Isochronous Cycles
On an Ethernet network, data is transmitted in small packets. Digital audio data must be
etized before transmission, and
The CobraNet equivalent of a packet is a bundle. A single bundle may contain data for up to
eight channels of 20-bit/48 kHz digital audio, or seven channels at 24-bit/48 kHz. Each bundle
consists of a preamble, destination address, source address, frame type, audio data, and FCS
(Frame Check Sequence) error checking.
Destination
Preamble
A bundle
Bundles are transmitted in isochronous cycles, and the cycle duration is 1.33 ms. There are
eight bundles per cycle. Each cycle starts with a beat packet, which is used for synchronization.
The last packet in the cycle can be used to transmit asynchronous serial data. The ACU16-C
and NHB32-C use this for power amp control, MIDI, and AD824 head-amp control.
Bundle Bundle Bundle
#1 #2 #3
The NHB32-C can transmit 4 bundles and receive 4 bundles simultaneously (i.e., 32 channels
in, 32 channels out). The ACU16-C can receive 4 bundles (i.e., 32 channels in).
CobraNet has a fixed latency of 5.33 ms (or 256 samples). This is mostly due to digital audio
packetization and unpacketization.
unpacketized upon reception.
Source Frame
CH
address address type
1
Bundle
Bundle Bundle Bundle
#4 #5
Isochronous cycle (1.33 ms)
Audio data
CH CH CH CH CH CH CH
FCS
2 3 4 5 6 7 8
Bundle Bundle
#6 #7 #8
CobraNet, ACU16-C & NHB32-C Guide
pack-
Async. serial
data packet
5