(b)  
The engine No. 2 and 3 takeoff discretes from the three EIUs send outputs to the R/T analog I/O module to arm the automatic turn-on software logic. These discretes are called qualifier discretes which enable the windshear detection while in the takeoff mode (engines above idle).

 (c)  
These inputs inhibit windshear opertion at all times for the safety of maintenance personnel when normal ground maintenance is being performed. One exception is when maintenance personnel are performing engine acceleration or deacceleration tests. The receiver/transmitter cicuit breakers must be opened during these engine tests.

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 (d)  
The PWS fail output is generated by the analog I/O module as a fail lamp enable signal. The PWS fail output from the R/T goes to the three E1Us for display on the EFIS/EICAS interface unit of the Central Display System (AMM 31-61-00).

 (e)  
The PWS fail outputs from the R/T causes the EFIS/EICAS

 interface unit to provide system status and advisory messages.PWS Electrical Power

 (a)  
Normal operation of the X-band airplane electrical power and system turn-on operate the same as described in the previous paragraphs.

 (b)  
In addition a dual system comm out signal from the left R/T goes to the right R/T and becomes a dual system comm in signal. An identical signal goes from the right R/T to the left R/T.

 (c)  
If the left R/T is selected, a 28v dc signal will cause the right R/T fail lamp driver and automatic turn-on circuits to be disabled.

Weather Radar Control Functions

 (a)  
Several control and data busses send ARINC 429 and 453 data between weather radar and various interfacing systems. Control bus 0 from the control panel sends ARINC 429 system mode, gain, and tilt data to the left and right R/Ts. Control Bus 1 and 2 from the left and right CDUs send EFIS control panel data to the respective R/Ts. Control busses from the left and right CDUs send weather radar display enable signals and range data to the NDs.

 (b)  
Within the receiver/transmitter, the input control data is fed to the microprocessor (MP) and digital input/output (I/O) and the antenna stabilization circuits. The timing, control, and monitoring circuits provide timing, control, and monitoring of all functions of the receiver/transmitter.

Control Panel Functions

 (a)  
The mode selector and gain control in AUTO send inputs directly to the control panel left or right microprocessor. Manual gain and antenna tilt inputs are processed by an analog-to-digital converter and sent to the left or right microprocessor.

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 (b)  
The mode selector, along with the gain control and TILT mode select switch in AUTO, send inputs directly to the control panel left or right microprocessor. Manual gain and antenna tilt inputs are processed by an analog-to-digital converter and sent to the left or right microprocessor.

 (c)  
The digital outputs of mode gain and tilt are sent from the microprocessor to left and right ARINC 429 transmitter on control bus 0 to the left and right receiver/transmitters repectively.

 (d)  
The system (SYS) transfer switch sends the system on/off discrete signal to either the left or right receiver/transmitters. In addition the switch is used to provide 28 volt dc switching of the waveguide switch as explained in the electrical power and power control circuits operation.

 (e)  
The mode selector switch positions operations are explained as follows: 1) TEST position initates a system self-test operation and

 develops a test pattern.
 2)  WX position selects the normal weather detection mode of operation which shows areas of significant rainfall as colored areas on the indicator. Terrain may also be displayed.
　
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