Complex partitioned system setup - Johnson Controls - LIT-1201668 - System Integration - LonWorks Integration - 12.0

LonWorks Network Integration with Network Engines and LCS Technical Bulletin
Product
Integrations > Lonworks Integrations > LonWorks Integration
Document type
Technical Bulletin
Document number
LIT-1201668
Version
12.0
Revision date
2022-08-30
Product status
Active

About this task

This system comprises a single large LNS database containing all nodes in the system with multiple LCS85 servers. The LCS85 servers are segregated to communicate to different devices within the same network. Segregation is based on designating complete FTT-10 channels to each LCS85. You manually partition the system ensuring only specific LonWorks IP routers (or specific nodes) are mapped to the LCS85. No device can be mapped to both systems.

This system closely meets flat LonWorks system specifications and is still considered flat because any node can be bound to any other node in the system. The purpose of LCS85 server segregation is to break up the network into manageable pieces for incorporation into a Metasys system.

Partitioning a network is a way to manage large systems, but does require some caution. Consider the following issues when you partition a large system:

Procedure

  1. Partition the system carefully.

    Cleanly divide the system to provide easily understood system organization. Clustering all devices under a single router is one method to clearly partition the system. Keeping each part of the system isolated prevents numerous smaller problems.

  2. Consider command interference.

    Commands can interfere or clash with each other if two different LCS85 servers are commanding the same point in the field or if the same point is mapped to multiple objects. When commands clash with one another, the device carries out the last issued command. Systems that have this problem behave erratically.

  3. Isolate devices to one router and one server.

    When two LCS85 servers are communicating, each one checks message error rates (messages unsuccessfully communicated). The error rate rapidly increases if multiple units start communicating down to a single router because the router can only handle a certain amount of traffic on the FTT-10 channel. As traffic increases, error rates increase and may overload the server. In response, all LCS85 servers reduce their communication rate to reduce the error rates.

    In a situation where error rates are high, both LCS85 servers reduce their communication at the same time and in the same manner because all machines use the same algorithm. When the error rates decrease, they increase communication at the same time and same manner. If multiple units are competing for bandwidth on the same router, this rise and fall in traffic continues indefinitely. You can avoid this problem by keeping all devices under one router isolated to one LCS85 server.