Yamaha CL Series System Design Manual page 5

Here is how the Console ID affects operation. Because Console ID #1 controls some settings of the
R series units, there should always be a console with ID #1 in the system (unless R Remote software
is used instead of a mixing console):
R series Unit ID
When using multiple R series I/O rack devices in the system, make sure a unique ID number is set for
each device. There are many more Unit ID numbers available for R series devices: up to 32 for the
original Rio, and 128 for the newer Rio-D2 range. You will notice that the ID numbers are in
hexadecimal format.
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