Contemporary Control Systems AI Active Hubs - Manual (Page 17)

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2.6.1 Connecting Coaxial Cable Star Networks (-CXS)
There are generally two types of coaxial cables that are used
with ARCNET, RG-59/u and RG-62/u. RG-59/u is 75 ohm
cable which does not precisely match the impedance of the
transceivers used on the AI ports. This cable will work, but
communication distances are reduced compared to RG-62/u
because of the higher attenuation of RG-59/u cable. We
recommend RG-62/u because it is a better match to the
transceivers and a full 2000 foot segment distance can be
achieved using this cable. Both cables support male BNC
connectors which the -CXS port accommodates. When
connecting to a -CXS port, do not apply a terminator or BNC
“T” connector to the port. Simply connect the coaxial cable to
the BNC port.
2.6.2 Connecting Coaxial Cable Bus Networks (-CXB)
Some AI2 link and repeater models support coaxial bus
transceivers (-CXB) which allows the insertion of an AI at any
point within a bus segment. Usually, RG-62/u coaxial cable is
used to connect the various nodes and the AI requiring 93 ohms
of passive termination at the extreme ends of the bus segment.
This is accomplished using a BNC terminator (BNC-TER) and
BNC “T” connector (BNC-T) at each end. A BNC “T”
connector is then used to interconnect the various devices
within the segment. Make sure that all devices are -CXB
compliant.
If a bus segment is to be connected to a coaxial star port
(-CXS), connect the -CXS port only at the extreme ends of the
bus segment without a passive terminator. The -CXS port
effectively terminates the bus segment without the need for
additional termination.