TD873600-0IA
5
FIELD CONNECTIONS
The SBX20 is available in several transceiver options. Each transceiver,
which is matched to a particular cable type, is identified by a three-digit
suffix appended to the model number. The capabilities of each transceiver
differs.
-CXS Coaxial Star
There are generally two types of coaxial cables that are used with the -CXS
transceiver, 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 NIM. 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 NIM accommodates.
In a two-node system, simply connect the two -CXS NIMs together using
RG-62/u coaxial cable. The length of cable cannot exceed 2000 feet.
If more than two NIMs are used on a network, either an active or passive
hub is required. With passive hubs, a maximum of four NIMs can be
interconnected. Unused ports on the passive hub must be terminated with a
93 ohm (nominal) resistor. The maximum length between a passive hub port
and a NIM is 100 feet.
Active hubs provide overall better performance than passive hubs since
greater distances can be achieved along with a degree of isolation. Connect
each NIM to a port on the hub using RG-62/u coaxial cable. This length of
cable cannot exceed 2000 feet nor can the length of cable between two
cascaded hubs exceed 2000 feet. However, up to ten hubs can be cascaded
thereby providing an overall cable length of 22,000 feet. Unused ports on
active hubs need not be terminated.
Figure 2. Bus segments can be extended
through active hubs.