User's Manual

SYSTEM DESCRIPTION AND INSTALLATION MANUAL
TCAS 3000 Traffic Alert and Collision Avoidance System
34−43−23
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Page 4−31
15 Dec 2005
Table 4−5. 41−Pin VSI/TRA Interface Descriptions
Connector Pin
Designation
Functional Description
J1−1 VERTICAL SPEED +DC REFERENCE INPUT:
Pins 1,2, and 3 are inputs to the VSI/TRA from an ARINC 575 air data computer
indicating vertical speed. Pin 1 is a +12 V dc regulated reference voltage from the ADC.
Pin 3 is a −12 V dc regulated reference voltage from the ADC. Pin 2 receives a +10 to
−10 V dc rate signal from the ADC. Also see pins 31, 32, and 33.
J1−2 VERTICAL SPEED DC RATE INPUT:
See pin 1.
J1−3 VERTICAL SPEED −DC REFERENCE INPUT:
See pin 1.
J1−4, 6 ARINC 565 VERTICAL SPEED AC INPUT: (J1−4 HIGH, J1−6 LOW)
Pins 4, 5, 6, and 16 are inputs to the VSI/TRA from an ARINC 565 air data computer or
IRS. A 26 V ac, 400 Hz reference signal is received on pin 5, (HI) and pin 16, (LO). Pin
4, (HI) and pin 6, (LO) provides an amplitude modulated 400 Hz signal with a maximum
voltage of " 6.25 volts. The RMS value of this signal is used by the VSI/TRA to compute
and display the vertical rate. The phase of this signal is compared with the reference
signal to determine if the rate is positive or negative. An in−phase signal equals a
positive rate, an out−of− phase signal indicates a negative rate. Also see pins 8, 31, 32
J1−5 VERTICAL SPEED 26 V ac, 400 HZ REFERENCE INPUT (HI):
See pins 4 and 16.
J1−8 VERTICAL SPEED VALID DISCRETE INPUT:
The VSI/TRA receives a 28 V dc signal from an ARINC 575 or 565 air data computer
indicating its valid operation. An “open” at this pin indicates an invalid vertical speed
signal from the ADC. This pin is only used when pins (1, 2, 3) or (4, 5, 6, and 16) are
used. Also see pins 1 and 4.
J1−9, 10 5−VOLT LAMP DIMMING INPUT: (J1−9 LOW, J1−10 HIGH)
The VSI/TRA monitors the cockpit lamp voltage bus at pins 9 and 10. This voltage may
be either ac or dc. The back lighting in the VSI/TRA is adjusted by and tracks this voltage
from 0.5 volts to 5 volts. If this input falls below 0.5 volts or is absent, the VSI/TRA sets
itself to a nominal level to prevent the display from going dark due to loss or failure of the
lamp dimming bus.
J1−11 ARINC 429 (B) TCAS TA/RA DATA BUS INPUT:
Paired with pin 26. These pins connect to a TCAS computer unit.
J1−12 ARINC 429 (B) VERTICAL SPEED NO. 1 INPUT BUS:
Paired with pin 27. These pins connect to Digital ADC No. 1 or PTM No 1.
J1−14 ARINC 429 (B) VERTICAL SPEED NO. 2 INPUT:
Paired with pin 30. These pins connect to Digital ADC No. 2 or PTM No. 2.
J1−15 CONFIGURATION STRAP COMMON INPUT:
This pin is the return line for the configuration strapping pins J1−17, J1−32 thru 38, and
J1−41.