Specifications

Chapter 2: 192 Digital I/O Overview 9
Optical (ADAT) In and Out
These Optical ports can be configured to func-
tion as two channels (stereo) Optical S/PDIF or
as a third set of eight channels of Optical
(ADAT) input and output.
In Optical S/PDIF mode, these ports support
two-channel Optical input and output at sam-
ple rates up to 96 kHz. In Optical (ADAT) mode,
sample rates above 48 kHz are not supported;
unlike Optical (ADAT) ports on the Digital I/O
cards, these Optical (ADAT) do not feature real-
time sample rate conversion.
LOOP SYNC In and Out
Loop Sync is a dedicated clock loop for synchro-
nizing multiple HD-series interfaces together.
Loop Sync uses a word clock signal based on
sample rates of either 44.1 kHz or 48 kHz. As
sample rate increases in the system, Loop Sync
continues to operate at a base rate of 44.1 kHz or
48 kHz, depending upon the higher rate.
The Loop Sync In and Out ports are standard
BNC connectors that output a 1x Loop Sync
clock signal. Loop Sync should only be used to
chain multiple Pro Tools|HD peripherals to-
gether.
EXT. CLOCK In and Out
The External Clock I/O ports are standard BNC
connectors that receive and output word clock.
These ports can be used to synchronize the
192 Digital I/O with any word clock-capable de-
vice.
The External Clock In port is configured by your
choice for Clock Source in the Hardware Setup
dialog. The External Clock Out is configured us-
ing the External Clock Out selector in the Hard-
ware Setup dialog.
AC Power
This connector accepts a standard AC power ca-
ble. The 192 Digital I/O is auto power-selecting
(100V to 240V) and will automatically work
with a standard modular cable to connect to AC
power receptacles in any country.
Primary Port
The Primary port is where the 192 Digital I/O is
connected to your Accel Core, HD Core, HD Ac-
cel or HD Process card using a DigiLink cable.
The Primary Port can also be connected to an
available Expansion Port on another
Pro Tools|HD audio interface used in the sys-
tem.
The Primary DigiLink port sends and receives 32
channels to and from the Pro Tools|HD cards (or
other interface). Channels 17–32 (if active) are
passed through to the Expansion port or the
Legacy port.
Because crucial timing data is passed
through the Loop Sync and Word Clock ports,
you should use high-quality, 75-ohm RG–59
cables for making connections.