Rockwell Automation 1770 DH,DHII,DH485 CABLE - Manual (Page 29)

Planning a Data Highway or Data Highway Plus
Cable System
Chapter 2
2-13
Important: Remember that the maximum cable length of the trunkline is
10,000 feet (3050 meters), and that dropline cables must be no more than
100 feet (30.5 meters) in length. If possible, keep the dropline cables
longer than 10 feet (3.0 meters) in length.
Selecting the shortest path for routing the cable will help minimize the
amount of cable you will need. The specific details of planning such a
cable route depends upon the needs of your network.
When determining cable lengths, be sure to follow the guidelines outlined
in the section, ‘‘Harmful Environmental Factors” later in this chapter.
ATTENTION: When determining cable lengths, do not allow
tension to be exerted on the cable. Tension on the cable can
damage the cable and connectors. To minimize tension, allow
sufficient slack in the cable.
Whether you plan to use the 1770-SC station connector or the 1770-XG
connector kit, you must order a connector for each node you want to link to
the network
If you plan to add nodes at a later date, you should order and install the
cable and connectors for these additional nodes when you install the initial
cable system. This will help avoid the disruption of recabling after the
network is in operation.
Important: If you install additional station connectors, do not install the
dropline to the connector. An unattached dropline acts as an antenna for
network noise.
Important: Remember that a DH or DH+ network can have no more than
64 nodes. Each station connector on the trunkline counts as one of those
nodes, even if no dropline or device is connected to that station connector.
Selecting the Number of
Station Connectors