(4) Electrical characteristics
(a)
Power supply voltage: 115 V/400 Hz.
(b)
Consumption: 11 W (mean value during data transfer).
(c)
The MDDU senses undervoltages less than 80V as power interrupts. The type of restart depends on the duration of the interrupt.
1 Voltage more than 80 V:
_
No power interrupt is detected.
2 Voltage less than 80 V:
_
a and power interrupt less than 20 ms:
_ No power interrupt is detected (transparency time).
b and power interrupt greater than or equal to 20 ms and less
_ than 200 ms: A power interrupt is detected. The MDDU continues the program as soon as power returns (recovers transfer operation by starting at the beginning of the file being transmitted) (warm start).
c and power interrupt more than 200 ms and less than 5 s:
_ The MDDU restarts the program from the beginning (reads configuration file) (cold start).
d and power interrupt more than 5s:
_ The MDDU restarts the program from the beginning (cold start) and executes a Power On Self Test (POST) if in ground configuration.
B. DLRB Description
(Ref. Fig. 006)
The face of the DLRB includes four ASN-E0390 DD 01 P connectors named A, B, C, D, one identification plate and a free space for the buyer's CMS sticker.
(1) Mechanical characteristics
(a) Size
1 Height: 170
_
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Data Loading Routing Box (DLRB)
Figure 006
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_
3 Depth: 162
_
(b)
Weight: 2 kg (plus or mimus) 0.2 kg).
(c)
Attachment: by four holes for screws of 5 mm dia.
(2) Electrical characteristics
(a)
Power supply voltage: 28VDC
(b)
Consumption: 7.5 W (this power includes DLS consumption).
C. DLS Description
(Ref. Fig. 007)
The DLS is the remote unit which commands the DLRB. The user interface consists in a two-line LCD display, and ON/OFF switch and three keys on the front panel.
The ON/OFF switch allows to put DLRB in "active or inactive" state through the ON/OFF discrete output. The ON/OFF switch does not command directly the DLS power supply. The DLS is powered by the DLRB through its supply outputs.
When powered on, the two-line screen displays the name of the LRU channel and its state (selected/not selected). The PREV and NEXT keys allow scrolling inside the allowed LRU namelist. The SEL CTL key allows a LRU to be selected or deselected.
(1) Mechanical characteristics
(a) Size
1 Height: 46.8 mm
_
2 Width: 146
_
3 Depth: 146.9
_
(b)
Weight: 0.5 kg (plus or minus 0.125 kg)
(c)
Attachment: by four quarter-turn fasteners.
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Data Loading Selector (DLS)
Figure 007
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(2) Electrical characteristics
(a)
Power supply voltage: 28VDC from DLRB.
(b)
Consumption: 1.2 W.
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7. Operation_________
A. MDDU
(Ref. Fig. 008)
(Ref. Fig. 009)
The MDDU contains two su-assemblies:
-an electronic unit
-a disk drive.
(1) The electronic unit is composed of
(a) Power supply board
From a 115V/400Hz input, the power supply board supplies the DC sources (+5VDC, +12VDC and -12VDC) used by the MDDU components in normal operation.
In addition, it supplies a special voltage (+ 5VDC/P) which is protected for 250 ms. This is provided to maintain power on the RAM buffers Central Processing Unit (CPU) during a power interrupt less than 200 ms to perform a warm start.
(b) I/O board
This board is wired to the MDDU rear connector and provides the following I/Os:
-ARINC 429 BUS
-Discretes
-RS-232 link.
This board is not involved in the RS-232 circuitry. It simply ensures connection between the MDDU rear connector and the CPU/Floppy Disk Drive Control (FDDC) board that processes this link.
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