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ROC827 Instruction Manual
Issued Mar-06 Communications 5-8
You can link Ethernet networks together to form extended networks using
bridges and routers.
Table 5-6. Ethernet Signal LEDs
Signal Function
RX Lit when currently receiving.
TX Lit when currently transmitting.
COL Lit when Ethernet Packet Collision detected.
LNK Lit when Ethernet has linked.
Use a rugged industrial temperature HUB when connecting Ethernet
wiring in an environment that requires it.
The IEEE 802.3 10BASE-T standard requires that 10BASE-T transceivers
be able to transmit over a link using voice grade twisted-pair telephone
wiring that meets EIA/TIA Category four wire specifications. Generally,
links up to 100 meters (328 feet) long can be achieved for unshielded
twisted-pair cable.
For each connector or patch panel in the link, subtract 12 meters (39.4
feet) from the 100-meter limit. This allows for links of up to 88 meters
(288 feet) using standard 24 AWG UTP (Unshielded Twisted-Pair) wire
and two patch panels within the link. Higher quality, low attenuation
cables may be required when using links greater than 88 meters.
The maximum insertion loss allowed for a 10BASE-T link is 11.5 dB at
all frequencies between 5.0 and 10.0 MHz. This includes the attenuation
of the cables, connectors, patch panels, and reflection losses due to
impedance mismatches to the link segment.
Intersymbol interference and reflections can cause jitter in the bit cell
timing, resulting in data errors. A 10BASE-T link must not generate more
than 5.0 nanoseconds of jitter. If your cable meets the impedance
requirements for a 10BASE-T link, jitter should not be a concern.
The maximum propagation delay of a 10BASE-T link segment must not
exceed 1000 nanoseconds.
Crosstalk is caused by signal coupling between the different cable pairs
contained within a multi-pair cable bundle. 10BASE-T transceivers are
designed so that you do not need to be concerned about cable crosstalk,
provided the cable meets all other requirements.
Noise can be caused by crosstalk of externally induced impulses. Impulse
noise may cause data errors if the impulses occur at very specific times
during data transmission. Generally, do not be concerned about noise. If
you suspect noise related data errors, it may be necessary to either reroute
the cable or eliminate the source of the impulse noise.
Multi-pair, PVC 24 AWG telephone cables have an attenuation of
approximately 8 to 10 dB/100 m at 200°C (392°F). The attenuation of
PVC insulted cable varies significantly with temperature. At temperatures