Emerson Vission 20/20 Operation And Service Manual page 187

Appendix B • Vission 20/20 Application Procedures
NETWORK TOPOLOGY
RS422/RS485 Networking Topology
Many articles have been written about the different to-
pologies of RS422/RS485 networks. Vilter recommends
that a daisy chain topology be used for any RS422/RS485
network that incorporates a Vilter 20/20 panel as a net-
work slave node. Refer to Figure B-15.
USING A NETWORK ISOLATOR / REPEATER
The RS422/RS485 repeater/isolator can be used to pro-
vide a device on the serial network with isolation. The
isolator/repeater suppresses surges that may be present
on the network wires, and optically isolates and converts
unbalanced lines to balanced lines. It can also act as an
RS422 to RS485 convertor while providing the same
network isolation. Vilter stocks a network repeater/iso-
lator for the 20/20 panels – VPN 3485MS.
Figure B-15. 2-Wire Multidrop Network Using Terminating Resistors
Figure B-16. Wiring Diagram – VPN3485MS Device as RS422 to RS485 Convertor/Isolator
Vission 20/20 • Operation and Service Manual •Vilter/Emerson • 35391SC 2.0
USING VPN3485MS DEVICE AS A NETWORK
CONVERTOR
In Figure B-16 is a typical connection wiring diagram
for using the device as an RS422 to RS485 convertor/
isolator.
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