VIS CABLING

TM11-5830-263-20&P

Further, audio levels can be controlled to accent internal communication in emergency conditions. The

system interfaces with a loudspeaker and various types of headsets (CVC, CAPS, ACAPS, and CCH);

the loudspeaker connects to the MCS or to any FFCS/MOS and allows one-way communication to crew

or troops either being transported or working in close proximity to the vehicle.

The system incorporates an Auto Reconnect Circuit (ARC) that continually monitors the system bus. If a

break occurs in the ring bus, the ARC automatically restores system connectivity and informs the operator

of the malfunction.

1.15.

VIS CABLING

VIS is interconnected using a single type of cable called a highway cable. Data, power, and analog

signals are carried by a seven-conductor cable, which incorporates internal and external shields as

shown in figure 1-2. The external shielding prevents cross talk from external sources; the internal

shielding prevents cross talk internal to the cable. This cable carries the VIS data bus on the inner

shielded twisted-pair of conductors. Two conductors carry conditioned system power for distribution to all

units, two conductors carry the conditioned Active Noise Reduction (ANR) power, and the seventh

conductor carries the analog audio signal for the MOSs. The two shields are combined with the zero volts

ground on the vehicle body. The power supply conductors and intercom audio are connected in a ring.

+28VDC CONDITIONED POWER SUPPLY

0 VDC CONDITIONED POWER

DATA + (ONE OF BALANCED TWISTED SHIELDED PAIR)

DATA - (ONE OF BALANCED TWISTED SHIELDED PAIR)

ANALOG AUDIO LINE

24VDC ANR SUPPLY

0 VDC ANR RETURN

Figure 1-2. Highway Cable Construction

a. Partial Cable Failure The data bus conductors are not connected in a complete ring but as a

bus which originates and terminates inside the MCS on the Automatic Reconnect Circuit (ARC).

The ARC monitors data bus activity at the terminating end of the bus. In normal operation there

will always be activity on the bus. If the ARC detects no bus activity (i.e., a break has occurred

somewhere on the data bus) it instantly activates the re-route circuit, connecting the originating

and terminating ends of the bus, thereby automatically reconnecting those units located

"downstream" of the cable break. The ARC is so quick in reconnecting the bus that its operation

normally goes unnoticed by the crew; therefore to alert the crew that a cable break has occurred,

the CPM reports a "ring unconnected (ru)" fault on the MCS display.

b. Total Cable Failure If any single VIS cable is totally severed, the system will continue to

operate without degradation in performance. The system reconfigures itself automatically (i.e.,

power is still available to each unit; the ARC detects the break and reconnects any unconnected

units; a "ring unconnected (ru)" warning is displayed on the MCS by the CPM).

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