LonWorks Wiring Guide
Maximum Number Of Devices
Up to 64 transceivers are allowed per network segment. If your network requires more than 64 transceivers a
repeater is then required to extend your network
Maximum Cable Length
The maximum length of a chain is related to its transmission speed. The longer the chain, the slower the
speed. Using proper cable, LonWorks supports a baud rate of 78 kilobits per second for distances up to
1600-ft (500 m) in free topology and 8800 ft (2700 m) in bus topology with double terminations.
If you require a maximum network length of more than 1600-ft (500 m) or 8800 ft (2700 m), then a
repeater is required to extend the network.
Repeater
In the event that the limits on the number of transceivers or total wire distance are exceeded, a physical
layer repeater can be added to interconnect two or more network segments. A repeater will double the
overall channel capability, including node count and network extent, but not bandwidth. Note that only
one physical layer repeater should be placed in series between any two nodes on a channel. If
additional cabling or network bandwidth is required, then a LonWorks Router should be used in place of
a repeater.
Terminators
LonWorks network segments requires termination for proper data transmission performance. The type of
terminator varies depending on whether shielded or unshielded cable is used. Free topology and Bus
networks also differ in their termination requirements. The following sections describe the various terminators
and terminations procedure.
Free Topology Network Segment
In a free topology segment, only one termination is required and may be placed anywhere on the
free topology segment. There are two choices for the termination:
1. RC network with Ra = 52Ω±1%, 1/8W
2. LPI-10 Link Power Interface, with jumper at “1 CPLR” setting.
Doubly Terminated Network Segment
In a doubly terminated bus topology, two terminations are required, one at each en of the bus.
There are two choices for each termination:
1. RC network with Ra = 105Ω±1%, 1/8W
2. LPI-10 Link Power Interface, with jumper at “2 CPLR” setting.
Only one LPI-10 interface is supported per segment. The other terminator must be an RC-type.
LonWorks Wiring Guide
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