SKY899
Installation Manual
009-11900-001
Appendix A - Page A-1
Revision F
July 18, 2013
Appendix A
SKY899 Interface
Signal Name & Cable Characteristics
A.1 INTRODUCTION
This appendix defines the electrical characteristics of all input/output signals to the TRC899 and the
labels for the ARINC-429 data bus. Sufficient data is included to perform an electrical load analysis for
the aircraft. The interface characteristics contained in this appendix are fully compatible with ARINC
specifications where noted. Connection information identifies connector-pin and signal names as they
appear on interconnect wiring diagram, figure A-1 shows P1 connector pin locations and signal names.
NOTE
External isolation diodes are not required and SHOULD NOT be installed.
A.2 ELECTRICAL CHARACTERISTICS
SIGNAL
CHARACTERISTICS
Altitude (Gilham Code) /
These uncorrected barometric signals are Gilham code (or gray code)
Encoding Altimeter Input
inputs coming from an airdata computer or encoding altimeter (see
paragraph 2.11). These 11 lines may be connected in parallel with the
aircraft transponder. If the aircraft is equipped with selectable altitude
encoders, connect the altitude inputs so that SKY899 is always
connected to the selected encoder. (Reference ARINC 572-1.)
NOTES
1. Only one altimeter input source (gray code or ARINC-429, not both)
should be connected. The altimeter input should be from the same
source that is interfaced with the transponder or at least as accurate
as that source, i.e., ± 125 ft.
2. If the aircraft has switched encoders that use 28V RETURN or
AIRCRAFT GROUND as reference for encoder selection, then
ALT_COMMON (P1-72) should be left unconnected.
3. If altitude D2 is not used P1-70 should remain unconnected.
CONNECTION
Connector-Pin
Signal Name
P1-56
ALT_A1
P1-57
ALT_A2
P1-58
ALT_A4
P1-59
ALT_B1
P1-60
ALT_B2
P1-61
ALT_B4
P1-67
ALT_C1
P1-68
ALT_C2
P1-69
ALT_C4
P1-70
ALT_D2
P1-71
ALT_D4
P1-72
ALT_COMN
The document reference is online, please check the correspondence between the online documentation and the printed version.
