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B&E Technologies CT-N128

CorNet ARCNET Adapter PC Fiber ST 820nm QNX

DESCRIPTION
This is an ARCNET fiber optic adapter for QNX 2 and QNX 4 networks. The CorNet ARCNET Adapters - Fiber Optic offers high resistance to radio frequency interference. This is due to glass fiber being used as the medium to transmit the data packets across the network. Since glass is an insulator rather than a conductor of electric current, this medium cannot be affected by "noise" from other electrical sources, such as motors, radio transmitters, or lightning. With fiber optics, light is the source of energy that permits this transmission of data.

OPERATING ENVIRONMENT
Power:	+5V DC +/-5% @ 0.5A maximum (240 mA typical)
Operating Temperature:	0 to +55ºC
Storage Temperature:	-40 to +125ºC
Humidity:	5% to 80% (non-condensing)

ARCNET LAN INTERFACE
Two ST connectors
820nm to 850nm
Modified Token Passing Local Area Network
2.5 Megabaud transmission rate
Supports up to 255 nodes
Requires only 8 kbytes of Address Space
IBM PC, XT, AT and compatible
Switch selectable memory map base address (CC00,CE00,DC00,DE00,EC00,EE00)
Menu selectable node ID and interrupt level (levels 2,3,4,5,6 & 7)
2 KB dual ported RAM buffer for high speed interleaved message transfer
Software reset capability
Optical Power Budget:


PHYSICAL SPECIFICATIONS
Short length 8 Bit ISA Bus Card ( 4.97" long )
Switch selectable memory map base address
green LED indicates that the network is operating normally
red LED indicates node activity

INSTALLATION CONSIDERATIONS
Fiber Optic Cable Type	Dual Fiber
	Graded Index (Multi-Mode)
	62.5/125µm or 100/140µm
	ST connectors

Cable specifications include a standard connector loss for both ends of a single cable. It is recommended to allow 2dB of loss to allow for dirt and cracks in the connectors for any given link. Each fusion splice typically adds 0.25 dB loss, and barrel connector splices are the sum of the barrel connector and two end connector losses. All these factors result in loss along the line and must be considered.

Maximum Distance per Segment
A segment is the cable between two hubs or a hub and a card on the network. The maximum length of a segment of fiber optic cable is dependent on the quality, size, connectors, splices and rating of the fiber optic cable. The most important fiber optic cable specification is the attenuation per kilometer. In combination with the link budget shown previously, the maximum segment length can be calculated.

For example, consider a fiber optic cable with the following specifications:
-62.5/125µm
-Maximum attenuation 3.0 dB/Km
-No splices in entire cable length
-ST connectors on both ends
-Grade F, OFNR (UL Listed Riser)
-850 nm

From the Optical Power Budget chart the minimum Link Budget is 9.9 dB. Allowing the recommended 2 dB margins, the maximum segment length is then:

Max. Segment Length

Maximum Network Span
The maximum span defines the longest signal path length between any two nodes in the network. This determines the maximum end to end propagation delay. ARCNET controller chips have several internal timers based on the maximum propagation delay for a particular timeout level. A signal is allowed to pass through up to ten hub delays plus 2000ft [609m] of a coax cable at each segment to determine the standard propagation delay times. This becomes 22,000ft. [6705m] for a coax network. Since the velocity of propagation is lower in fiber optic cable, the network span is reduced. The maximum span for a network connected entirely with fiber optic cable using standard time-outs is approximately 18,500 ft. [5600 meters].

CONFORMS TO THE FOLLOWING STANDARDS
ARCNET:	ANSI 878.1
EMC:	EN 50082-1 (Immunity)
	IEC 801-2:1991
	4KV Contact, 8KV Air
	IEC 801-3:1984
	3V/m
	IEC 801-4:1988
	0.5 KV Signal line,
	1 KV Power line
European CE compliance