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Option 5 – Power line carrier transceivers
These modules are designed to be used with couplers that interface between the node and the power
line. As such, the PLT-22 transceiver and the power line coupler handle any termination issues.
Any standard 50W BNC cable may be used to connect the LM105-P50 to its line coupler. Because
the transmission medium is existing power line cable, the user will usually not have a choice in
what cable is used. The PLT-22 compensates for this by operating at a much lower data rate than
other transceivers (5Kbps).
Option 6 – Free Topology Transceiver
Free topology networks require only one terminator per network segment. It may be located
anywhere in the segment, regardless of the topology. For Option 6 boards connected in a strictly
bus-type topology, a second termination network may be added which will nearly triple the
allowable network length. The circuit in Figure 3 will properly terminate a Free Topology
network. Jumper JP3 must be left open to disable the LM104-P50’s onboard termination.
105W, 1%, 1/8W
100mF, 50V
100
mF, 50V
Figure 3. Free topology network terminator circuit.
Free topology networks have the widest choice of qualified cable types. Like twisted pair
transceivers, 22AWG (0.65mm) Level IV cable and standard TIA 586A Category 5 network cable
may be used. Echelon has also certified Belden 8471 (PVC insulation) 16AWG (1.3mm) cable and
Belden 85102 (Tefzel insulation) 16AWG (1.3mm) cables for use with free topology networks. A
European standard cable, JY (st) Y 2x2x0.8, also meets Echelon’s rigorous standards.