Hitachi S10mini LQS070 Hardware Manual page 44

6 CABLING
②③ Main line and drop line
Communication cables connected to the network can be classified into two types. A
main line is a bundle of cable having terminating resistor attached at both ends. A
cable splitting out from the main lines as well as cables splitting from the drop line is
also a drop line. Each node is connected to a drop line. Dedicated 5-wire cables
(thick cabled and thin cables) are used as communication lines.
④ T-branch device tap
Main lines and drop lines are connected by T-branch device taps in the DeviceNet.
Besides, TB (terminal block) can also be used to connect drop lines.
⑤ Connector
There are two types of connectors that connect communication cables to a node and to
a T-branch tap. The open-type connector is preferably used to connect a
communication cable to a D.Station module and to a T-branch tap.
⑥ Terminating resistor
In the DeviceNet network, terminating resistors (121 Ω±1%)must be attached to both
ends of the main lines. Out of many methods, the use of terminal blocks (TBs) and
their terminating resistors are recommended.
⑦⑧ Power taps and communication power supply
To communicate using the DeviceNet, supply power (24 VDC) to each node connected
to the network through power taps. T-branch taps and terminal blocks (TBs) can be
used to connect to the network.
⑨ Network grounding
Ground the shield of the network cable only at one point near by the center of the
network to avoid grounding looping. There are many ways of grounding: grounding
at D.Station module, grounding from a tap, and grounding from a terminal block (TB).
A grounding method using T-branch device tap in the sampler below.
Other recommended components of a DeviceNet control mechanism (than the nodes) are
listed below. "No." column corresponds to the components No.
When a terminal block (TB) is used, a terminal block, screws for the terminal block, and
solderless terminals for the communication cables are also required in addition to the
components listed below.
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