Contemporary Control Systems QuickLink Active Hubs - Manual (Page 5)

-CXB Coaxial Bus
For hub -less systems, the -CXB transceiver can be used. NIMs are
interconnected with RG-62/u cables and BNC Tee connectors. Each -CXB
NIM represents a high-impedance connection in both the powered and
unpowered states. Therefore, passive termination must be applied to both
ends of a bus segment. Use BNC style 93 (nominal) ohm resistors at each
end. The maximum segment length is 1000 feet and the maximum number
of NIMs that can be connected to a segment is eight.
To extend a bus segment beyond 1000 feet, an active hub is required. If the
hub port is of the -CXS type, connection can be made if a few simple rules
are followed. Only connect this bus segment at the end of a segment. Do
not connect the hub to the middle of a segment since the hub port is not of
the high-impedance type. Do not terminate the end which attaches to the
hub port since a -CXS port effectively terminates the end of a bus segment.
Simply remove the BNC Tee connector and terminator from the segment end
and attach the cable directly to the hub port. The opposite segment end still
requires termination if no hub connection is being made.
Figure 4 — A hub is required to extend bus segments.
-TPS Twisted-Pair Star
In a twisted-pair star system NIMs and hubs are interconnected in a point-
to-point fashion using either shielded or unshielded twisted-pair cable. A
NIM can connect to another NIM or to an unused port on a hub. Hub-to-hub
connections are allowed. A NIM such as the PCX-TPS can connect directly
to a QL-TPS port directly using a non-inverting cable.
Figure 5 — QL-TPS connected in a star configuration.
TD990300-0I
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