
B-64014EN/03 APPENDIX A.TROUBLESHOOTING
- 165 -
A.2 CHECKING CONNECTION WITH THE TRUNK
General notes are provided below. For network installation, consult
with specialized vendors or manufacturers. Run cables away from
noise sources.
The descriptions below are not applicable if the network is configured
using only those hubs that have Ethernet boards connected.
• When the trunk is based on 10BASE-5
(1) Make sure that a transceiver is attached to the trunk
correctly.
- If a transceiver is attached correctly, the resistance
between the trunk shield and central conductor is about
25Ω (when a terminating resistor is attached).
- A special tool is required to attach a transceiver. (No
special tool is required, depending on the manufacturer.
For details, refer to the installation manual of each
transceiver.)
- Do not attach a transceiver again to a point where a
transceiver was once attached. (Otherwise, the cable
can be damaged.)
(2) Make sure that transceivers are attached at proper intervals.
- Transceivers must be attached at intervals of 2.5 m or
more. It is recommended that transceivers be attached
at intervals of an integral multiple of 2.5 m. Usually,
marks indicating installation points are provided on the
trunk cable.
(3) Make sure that terminating resistors are attached.
- A terminating resistor must be attached to each end of
the trunk cable. (Resistance: 50Ω)
(4) Make sure that the trunk cable is not longer than 500 m.
(5) Make sure that the cable (transceiver cable) used for
connection between a transceiver and the hub is not longer
than a specified limit.
- Usually, the maximum allowable length of a
transceiver cable is 50 m. However, the maximum
allowable length of a cable with a smaller diameter
may be shorter than 50 m. So, check the specifications
of each cable.
• When the trunk is based on 10BASE-2
(1) Make sure that the length of each cable is 0.5 m or more.
- The minimum allowable distance between nodes
(units) is 0.5 m.
(2) Make sure that the trunk cable length (sum of the lengths of
cables) is 185 m or less.
(3) Make sure that terminating resistors are attached.
- A terminating resistor must be attached to each end of
the trunk cable. (Resistance: 50Ω)