Contemporary Control Systems EXP Expansion Modules User Manual - Manual (Page 14)

left-most side of the other connector. This is a straight-through
cable which is used exclusively to connect -TPS ports. If the
cable color on the left side of a connector appears on the right
side of the other connector, this inverted cable will result in
operational problems with your twisted-pair network.
2.5.4 Connecting Twisted-Pair Bus Networks (-TPB)
The -TPS transceivers use internal BALUNs and, therefore, are
not directly compatible with twisted-pair bus networks. All
-TPS systems must be tied in either a star (one hub and multiple
NIMs) or distributed star (multiple hubs and multiple NIMs)
topology. Under no circumstances should more than two -TPS
ports be connected to the same cable. However, a -TPS port can
terminate the ends of a -TPB network. Connect one end of the
bus segment to a -TPS port without passive termination. Do not
attach a -TPS port to the middle of the bus segment. It will be
necessary to invert the wiring sense at the -TPS port since the
-TPS port has inverted polarity to a -TPB port (BALUNs
introduce a signal inversion).
2.5.5 Connecting Fiber Optic Cable (-FOG), (-FG3)
Single mode fiber optic cable is available in one size and
multimode fiber optic cable is typically available in three sizes,
50/125, 62.5/125, and 100/140. The larger the size, the more
energy that can be launched and, therefore, the greater the
distance. Two connectors are supported
— the SMA and the ST.
The conventional SMA connector offers a threaded termination.
When this type of connection is tightened excessively, the fiber
optic cable can break resulting in unreliable communications.
Also, the degree of tightening affects the optimum throughput of
the cable. Depending upon the degree of tightening, fiber
alignment can vary from the optimal coupling, thereby
introducing some attenuation. The ST connector alleviates both
of these problems but is generally more expensive than the SMA
connector. The ST provides a bayonet style connector similar in
operation to a BNC coaxial cable connector.
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