User's Manual

TY91/TY92 VHF Radio Installation Manual 11 April 2012
00839-00 Issue AA
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24 Trig Avionics Limited
5.8 TC90 Controller Interface Details
5.8.1 TMAP Bus
TMAP is a Trig proprietary bus based on RS485 signalling. It provides a bi-
directional interface between the VHF radio and the control head. Each TMAP
interface comprises a balanced pair of signals, called A and B, both of which
must be connected for communication to work.
TMAP A and B lines on the controller should be connected to the
corresponding A and B lines of either TMAP1 or TMAP2 on the TY91/TY92.
5.8.2 RS232 Input
The RS232 input allows certain GPS receivers to preload the standby and
active frequencies. The TC90 understands the Apollo SL40 protocol
($PMRRC) based on NMEA, at a speed of 9600 bps, and responds to message
types 1, 4, 5 and 6.
The RS232 output can be used for status monitoring of the radio if required.
5.8.3 Remote ON
This output is connected directly to the Power/Mode switch on the TC90, and
should be connected to the Power ON discrete input of the TY91/TY92.
5.8.4 Power
The TC90 uses 12 volts which is available from the TY91/TY92 VHF radio.
This input should NOT be connected to aircraft power.
5.8.5 Step Button
The step button is used to allow remote operation of the radio, and is typically
used in a helicopter. Each time the step input is grounded, the next memorised
frequency is copied to the standby position. The input is active low, and will
be asserted when the voltage to ground is pulled below approximately 4 volts.