Contemporary Control Systems PC10420 Adapters - Manual (Page 9)

TD874100-0IH
9
strength divided by the light receiver sensitivity expressed in dB. The link
loss budget, which includes losses due to cable and connectors, must be less
than the power budget. Assuming cable attenuation of 3.5 dB/km, up to
2 km of 62.5
µ m fiber optic cable can be used per segment.
-TPB Twisted-Pair Bus
The -CXB transceiver can be modified to drive a balanced cable system
with the addition of some parts. This configuration is called -TPB and it
supports shielded or unshielded twisted-pair cable such as Category 5. Dual
RJ-11 connectors replace the single BNC connector in order to support the
popular modular plug connectors. For convenience, a three-position screw
terminal connector is also provided (see Figure 7). Follow the connector pin
assignments in Tables 4 and 5 when using these connectors or when mixing
cable types. Wiring between NIMs is accomplished in a daisy-chain fashion
with point-to-point cables connecting the various NIMs to create a bus
segment. The end NIMs will have one vacant RJ-11 socket which is to hold
the RJ-11 style 100-ohm terminator required to terminate the end points of
the bus segment. When terminating the screw terminal connector, install a
100 ohm, 1/4 watt resistor across terminals 1 and 2. Use twisted-pair cable
and observe polarity. Modular plugs must be installed on this cable so that
they do not invert the signals. Most satin cable does not twist the pairs nor
maintain signal polarity. Do not use this cable. To test for the proper cable
connections, hold both ends of the cable side by side with the retaining clips
facing the same direction. The color of the wire in the right-most position of
each plug must be the same if there is no inversion of the cable. If this is not
the case, the cable is inverted. Up to eight -TPB NIMs can be connected to
one segment which cannot exceed 400 feet in length.
The overall distance of a twisted-pair network can be expanded beyond 400
feet if hubs are used. Use a hub port that supports the same -TPB interface.
Figure 5—TPB NIMs are connected in a daisy-chain fashion
with terminators inserted at both end NIMs.
-485D DC Coupled EIA-485 (Non Backplane Mode)
The PC10420-485D supports DC coupled EIA-485 communication via a
daughter board which replaces the coaxial hybrid transceiver. This daughter
board receives the conventional P1 and P2 pulses intended for the coaxial
hybrid transceiver and converts them to an elongated P1 pulse (the width is
equal to P1 and P2) suitable for the EIA-485 differential driver. Therefore,