Bi-Phase/Tach/Gpi/Pilot Port Interfacing Notes - DigiDesign SYNC HD Manual

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
SYNC peripherals have a total of four Relay-level
GPI outputs on pins 3/4, 3-10 of the DB25 con-
nector (see the circuit diagram GPI (TTL)/MTC
Outputs).
The GPI Relay outputs are intended to drive Re-
lay loads only.
94 SYNC HD Guide
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 interface, always check the electrical
specifications provided by the equipment
manufacturer, including voltage levels,
current, loading and polarity. Incorrect
wiring may damage your equipment, the
SYNC peripheral, or cause personal injury.