DigiDesign SYNC HD, Руководство пользователя

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SYNC HD Guide 92
Bi-phase/Tach/GPI/Pilot Port
Interfacing Notes
‹
The six opto-isolators are 6N137 devices. The
four GPI input ports pass through 390 ohm se-
ries resistors to the cathode. The two Bi-
Phase/Tach inputs pass through 634 ohm series
resistors to the cathode.
‹
The two TTL-level GPI outputs are driven by a
74FCT541. Each output passes through a 220
ohm series resistor.
‹
12 volts is supplied at the connector for the
purpose of driving the opto-isolators in film
tach applications. It is regulated and can supply
up to 100mA.
‹
For Tach, the “rate” input is “BIPHA_I” and
the “direction” input is “BIPHB_I.” The polarity
of “BIPHB_I” is software programmable and de-
faults to “low” for “forward.”
‹
For Bi-phase, the default polarity relationship
between A and B is software programmable. 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).
‹
For highest signal quality, use a 25-pin cable
with individually shielded conductors.
GPI Relay Wiring for Fader-Start
The SYNC HD 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 Re-
lay 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 associated
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 demand-
ing power requirements, an external buffer or
relay circuit mst be used. This would typically be
constructed as part of a custom electrical inter-
face.
Each GPI TTL output is fully short-circuit pro-
tected via a 220-ohm series resistor.
Before attempting to wire any type of custom in-
terface, always check the electrical specifications
provided by the equipment manufacturer, in-
cluding voltage levels, current, loading and po-
larity. Incorrect wiring may damage your equip-
ment, the SYNC HD, or cause personal injury.