Honeywell
COMPONENT MAINTENANCE MANUAL
PART NUMBER 964-0452
I.B.1516A Page 53
Mar 30/01
23-12-01
to the control unit. If a fault state changes in an HF assembly, a LOW pulse is
initiated on the MINT line via an open-collector transistor.
Now the control unit can read the fault state via the module bus. A module select
is available for each HF assembly (MS1-MS4). During data transfer, only 1 mod-
ule select is on LOW at any time. Address lines (ADR0 to ADR2) can now ad-
dress a register on the module. The RD and WR lines specify the data direction.
The module bus data lines are connected to high potential via 100kΩ resistors.
Assemblies actuated by the module bus are:
– Amplifier
– Receiver/Exciter
– Power supply
7 A/D converter
The A/D converter transforms squelch and sense analog control signals into
digital values, thus permitting their further processing by means of software.
8 Parallel Input
The discrete input signals, LFTR and STRUT, are read in via the parallel inputs,
integrated in the USARTs.
(b) Interface D, A9
The interface accommodates all serial ARINC inputs and outputs, and parallel input
and output lines. Refer to Figs. 27 through 34.
1 ARINC input
There are 3 ARINC inputs on the interface (BITI, FRBA, FRQB), 2 ARINC con-
trol inputs and 1 ARINC BIT input. Only 1 ARINC control input is active at any 1
time; the active input port can be selected by means of the POSEL control line.
An ARINC data telegram has 32 bits in each case. The data are transferred on
2 lines, inverted and noninverted, respectively, according to an RZ code. A log-
ical 1 is transferred on the noninverting line as a high pulse, whereas, a logical
0 is transmitted as a LOW pulse. The levels are defined as the difference be-
tween the 2 lines. These apply:
HI: +6.5V to +13V
ZERO: +2.5V to –2.5V
LO: –6.5V to –13V
– ARINC word:
Format of an ARINC Word
Figure 27
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