Rockwell Automation 1770 DH,DHII,DH485 CABLE - Manual (Page 20)

Planning a Data Highway or Data Highway Plus
Cable System
Chapter 2
2-4
Station Connectors
Station connectors connect droplines to the trunkline and also link
trunkline segments together.
Important: 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.
There are two types of station connectors that can be used on a DH or DH+
network:
1770-SC station connector
1770-XG connector kit
The type of station connector you choose for your network depends upon
the characteristics of your installation.
If your installation: Use the: Because it:
Requires frequent moving and
reconfiguration of nodes
1770ĆXG connector kit Provides plugĆin type couplings that are quick and
easy to disconnect and reconnect.
Seldom requires changing a
node
1770ĆSC station
connector
Provides better physical protection and electrical
isolation, and does not require any soldering to
install.
You may use both types of connectors on the same DH or DH+ network.
For example, if you plan to frequently connect and disconnect a personal
computer to and from the network via an asynchronous module, you can
use a 1770-XG connector kit at that node and 1770-SC connectors at the
other nodes.
The following table lists other factors to consider when selecting a station
connector.
Characteristic: 1770ĆSC Station Connector: 1770ĆXG Connector Kit:
Initial Installation Screw Terminal Solder
Disconnection/Reconnection Screw Terminal PlugĆin
Grounding Enclosure Tied to Earth
Ground
None
Enclosure NEMA Type 13 None
Mounting BoltĆdown Enclosure None
Testing Required None Electrical Continuity