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ROC800-Series Instruction Manual
Revised Jul-14
Communications
5-9
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 greater than 400°C (752°F), use plenum-rated cables to
ensure that cable attenuation remains within specification.
When connecting two twisted-pair Medium Attachment Units (MAUs)
or repeaters together over a segment, wire the transmit data pins of one
eight-pin connector to the receive data pins of the other connector, and
vice versa. There are two methods for accomplishing 10BASE-T
crossover wiring:
Using special cable.
Wiring the 10BASE-T crossover inside the hub.
For a single segment connecting only two devices, provide the signal
crossover by building a special crossover cable, wire the transmit data
pins of one eight-pin connector to the receive data pins of the other
connector, and vice versa. Refer to
Figure 5-4
.
Signal
Signal
Pin 1 TD+
Pin 1 TD+
Pin 2 TD–
Pin 2 TD–
Pin 3 RD+
Pin 3 RD+
Pin 6 RD–
Pin 6 RD–
Figure 5-4. 10BASE-T Crossover Cable
5.7 EIA-232 (RS-232) Serial Communication
The built-in EIA-232 (RS-232), the LOI, and the communication
modules meet all EIA-232 (RS-232) specifications for single-ended,
asynchronous data transmission over distances of up to 15 meters (50
feet). EIA-232 (RS-232) communication provides transmit, receive, and
modem control signals. The LOI port also meets EIA-232D (RS-232D)
specifications.
EIA-232 (RS-232) communication has the following communication
port designations in ROCLINK 800.
LOI
– Local Port EIA-232 (RS-232D). Refer to
Section 5.5, Local
Operator Interface
.