Chapter 8: Wiring Diagrams and Pin Assignments 79
SYNC HD Cable Pin
Assignments
SYNC HD Serial Cable
A 12-foot Serial cable is included with the
SYNC HD to support connection of the SYNC HD
to the serial port on a Avid HDX card, HD Native
card, or HD Native Thunderbolt peripheral.
If you need to make a custom serial cable, refer to
the following pin assignment table for the SYNC-
to-Serial port cable.
Bi-phase/Tach/GPI/Pilot Port
Interfacing Notes
The six opto-isolators are 6N137 devices. The
four GPI input ports pass through 390 ohm series
resistors to the cathode. The two Bi-Phase/Tach in-
puts 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 pur-
pose of driving the opto-isolators in film tach ap-
plications. 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 HD has a total of four Relay-level GPI out-
puts 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.
SYNC-to-DigiSerial cable
Mini DIN 8-pin Male to Mini DIN 8-pin Male
12
21
35
44
53
68
77
86
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