Avid Technology Digidesign USD, Руководство пользователя, Страница: 92 / 96

Universal Slave Driver 88
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For Tach, the “rate” input is “BIPHA_I”
and the “direction” input is “BIPHB_I.”
The polarity of “BIPHB_I” is software pro-
grammable and defaults to “low” for “for-
ward.”
◆
For Bi-phase, the default polarity rela-
tionship between A and B is software pro-
grammable. The default setting for
“forward” is “A leads B.” This means that
the rising edge of A (0˚ phase) must precede
the rising edge of B (90˚ phase).
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For highest signal quality, use a 25-pin
cable with individually shielded conduc-
tors.
GPI Relay Wiring for Fader-Start
The Universal Slave Driver provides a total
of four Relay-level GPI outputs on pins 3/4,
3-10 of the DB25 connector (see the circuit
diagram GPI (TTL)/MTC Outputs).
The GPI Relay outputs are intended to
drive Relay loads only.
GPI Triggers
GPI output signals information:
0 (relay) = Play
1 (relay) = Record Ready
2 (relay) = fader start #1
3 (relay) = fader start #2
4 (TTL) = Stop
5 (TTL) = Record
Logical GPI numbers 0 through 3 are asso-
ciated with GPI relay outputs 0 through 3
(pins 3 through 10). GPI numbers 4 and 5
are associated with GPI TTL outputs 0 and
1 (pins 1 and 2).
GPI TTL WIring
The circuit can drive approximately 2 mA
through a load of 1.6K and maintain a logic
high level of 3.3V. In an application where
the equipment being controlled has more
demanding power requirements, an exter-
nal buffer or relay circuit mst be used. This
would typically be constructed as part of a
custom electrical interface.
Each GPI TTL output is fully short-circuit
protected via a 220-ohm series resistor.
Before attempting to wire any type of cus-
tom interface, always check the electrical
specifications provided by the equipment
manufacturer, including voltage levels,
current, loading and polarity. Incorrect
wiring may damage your equipment, your
USD or cause personal injury.