Polycom C16 - Manual (Page 53)

SoundStructure Design Concepts
3 - 9
The organization of the devices in this example would make it confusing to
properly terminate inputs and outputs to the desired physical inputs and
outputs. Any OBAM linking scheme other than the out-to-in, top-to-bottom
system, is not recommended as it will likely increase system debug and
installation time.
Due to this possible confusion of the numbering of physical inputs and
outputs, always connect the devices as recommended in the top-down order
connecting the higher OBAM OUT connection to the next OBAM IN
connection.
Physical Channel Summary
Physical channels and the OBAM Link were introduced in the previous section
as a simplification of how to refer to the actual physical inputs and outputs
when multiple SoundStructure devices are used. By OBAM Linking multiple
SoundStructure devices in an OBAM out-to-OBAM-in fashion from top to
bottom, the physical channel numbers in a multi-unit installation will be
sequential from 1 to the maximum number of inputs and outputs in the
system. No longer is a specific device identification required to uniquely
identify which input “1” is meant when there are multiple devices. When
multiple SoundStructure devices are used, there is only one input “1” and it
corresponds to the first input on the top device. The first input on the second
device will be input 17 (if the first device is a SoundStructure C16).
In the next section, the concept of physical channels will be extended as the
new concept of virtual channels is introduced as a way to easily and, as will be
shown, more flexibly reference the physical input and output channels,
simplifying both SoundStructure device setup and how SoundStructure
devices are controlled with external control systems.
Device Local Numbering System Numbering
A 1 - 16 1 - 16
B 1 - 16 33 - 48
C 1 - 16 17 - 32