User's Manual

Table Of Contents
SYSTEM DESCRIPTION AND INSTALLATION MANUAL
T
3
CAS/Part No.9005000
Table 4-2: T
3
CAS Computer Unit Interface Description
(Applicable to Part No. 9005000-11801 and -55801)
Connector
Pin
Designation
Functional Description
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 T
3
CAS 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 and digital source No.3 for valid data on the
ARINC 429 bus at RTP-5A and RTP-5B. This process is repeated until a valid flag
or data is detected.
Until a valid source is found, the TCAS function 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 function
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-12D thru RMP-
12F.
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 (Note 3) 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 TCAS 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.
RMP-3E
TCAS/ADS-B Discrete Output #4 (Lamp Driver)
Pub. No. 8600200-001, Revision 004
34-45-29
4-47
04 Nov 2014
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