User's Manual
SYSTEM DESCRIPTION AND INSTALLATION MANUAL
TCAS 3000 Traffic Alert and Collision Avoidance System
34−43−23
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Page 4−3
15 Dec 2005
Table 4−1. TCAS 3000 Computer Unit Loading/Gradient Specifications (cont)
Connector Pin
Designation
Functional Description
RMP−2E Spare Pin
RMP−2F, 2G 8−Ohm Audio Output: (RMP−2F [HI], RMP−2G [LO])
This is a synthesized voice output supplied by the TCAS computer unit. Its level is
programmable up to 4 Watts into an 8−ohm speaker. All aural traffic and resolution
advisories are announced over this output. See RBP−7A for audio level programming.
RMP−2H, 2J Radio Altimeter No. 1 ARINC 552/Analog Input: (RMP−2H [HI], RMP−2J [LO])
Normal aircraft configurations include either two digital or two analog radio altimeter
sources. The TCAS computer unit attempts to establish which type is present in order to
obtain data from one of the two available sources. TCAS first checks the radio altimeter
No. 1 valid flag at RMP−2K. If No. 1 is not valid then No. 2 valid is checked at RBP−3C.
If neither are valid then TCAS checks digital source No. 1 for valid data on the ARINC
429 bus at RMP−13H and RMP−13J. If none of the above are valid then the TCAS
checks the digital source No. 2 for valid data on the ARINC 429 bus at RBP−3D and
RBP−3E. This process is repeated until a valid flag or data is detected.
Until a valid source is found, the TCAS computer unit inhibits all surveillance, CAS, and
TA/RA display functions, records failures in maintenance memory, and sets the TCAS
system status discrete output at RMP−13K to invalid. The TCAS computer unit uses
radio altitude to inhibit advisories and aural annunciation when in close proximity to the
ground. This analog input No. 1, as well as analog input No. 2, can accept data as a dc
voltage from several types of radio altimeters. The type of radio altimeter is selected
using the program pins RMP−12B and RMP−12H thru RMP−12K.
RMP−2K Radio Altimeter No. 1 Valid Input (PO)
See RMP−2H. A valid condition is greater than 18.5 V dc. An invalid is open circuit.
RMP−3A Corrective Visual Advisory Discrete Output (NO)
The visual advisory discrete outputs are ground/open type discretes used to operate the
annunciator lights on the displays. This output is activated whenever a corrective aural
advisory is issued. The output remains active for the duration of the advisory unless
cancelled by the cancel discrete at RMP−3D. Only one visual advisory is active at a time.
The active state is ground and the inactive state is open.
RMP−3B Preventive Visual Advisory Discrete Output (NO)
Same as RMP−3A, except this discrete is activated whenever a preventative aural
advisory is issued.
RMP−3C Traffic Visual Advisory Discrete Output (NO)
Same as RMP−3A, except this discrete is active during a traffic advisory.
RMP−3D Cancel Discrete Input (NO)
This input discrete provides a means of canceling aural and visual alerts. It should be
connected to a cancel button (momentary ground type), if used. Groundprox/Windshear
has priority over the cancel button. Open is the inactive state and a momentary ground
(less than 50 ohms) produces the active state, canceling any active aural or visual alert.