Справочник Пользователя для Vista LM104-P50

 

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To maintain data transmission performance, network cabling must be terminated correctly.  
Termination requirements vary depending on the type of cable used for network connections – 
shielded or unshielded twisted pair - and the type of transceiver used. 
 
Cable Grounding 
 
The majority of LonWorks networks use twisted-pair wiring to interconnect the nodes, either 
shielded twisted pair (STP) or unshielded twisted pair (UTP).  If shielded twisted pair wiring is 
used, the shield of the cable should be grounded as illustrated in Figure 1. 
 
 

100nF, 100V, 10%
Metallized Polyester

470K

W, 5%, ¼W

SHIELD GROUNDING CIRCUIT

Shielded Twisted Pair

 

 
 

 
The 470K

W resistor safely bleeds off any static charge on the cable’s shield, and the capacitor  

helps avoid DC and 50/60Hz ground paths from being formed through the shield.  The cable shield 
should be grounded at least once per segment, and at each node if possible. 
 
 
Cable Wiring and Termination  
 
Termination of the network depends upon the type of transceiver used.  In some installations, the 
termination circuit included on the LM104-P50 may be used; in others, it should not be used.  The 
type of wire that may be used, per Echelon’s specifications, also varies by transceiver type. 
 
Option 1 – RS-485 
 
The RS-485-standard transceiver used in Option 1 boards specifies that a 120

W, ¼ W resistor 

should be installed across the network connections (pins 2 and 3 on P3) at every node (see Figure 
2).