TT26 ADS-B Transponder Installation Manual
24 January 2017
01633-00
Issue AC
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Trig Avionics Limited
15
5.5.2.1 TMAP over RS-485 Bus
Each TMAP RS485 interface comprises a balanced pair of signals, called A
and B, both of which must be connected for communication to work.
There are two sets of TMAP pins on the TT26, TMAP1 A and B, and TMAP2
A and B. This is to support future installation wiring options. The two sets are
identical, and either pair (TMAP1 or TMAP2) may be used to connect to the
control head; you will also need to add a ground wire.
5.5.2.2 TMAP over RS-232
When controlled using RS-232, the controller connects using pins 24, 25 and a
ground wire. The interface is fully compatible with RS-232 signalling levels.
5.5.2.3 Secondary Port
The unused RS-485 or RS-232 interface that is not being used as a control port
will be available for Altimetry input and output. The behaviour of the input
depends on system configuration, defined below. The output always reflects
the current altimetry source, regardless of input configuration.
Note: The TMAP RS-485 interface is optional, and may not be
present on systems using the RS-232 control pair on pins 24 and 25.
5.5.3
Auxiliary RS-232 Interface
The RS-232 interface on pins 5 and 7 is used for GPS data. The GPS can be
configured for either internal or external mode of operation as described in
section 6. The interface is fully compatible with RS-232 signalling levels.
5.5.4
Auxiliary Power
The TT26 provides 6.0 volts on pin 11. This output is intended for diagnostic
use, but can also be used to power small auxiliary equipment or a controller
providing current consumption does not exceed 300 mA.
