Excessive traffic - Metasys - LIT-12011034 - General System Information - Metasys System - Release 11.0

MS/TP Communications Bus Technical Bulletin

Product name
Metasys System
Document type
Technical Bulletin
Document number
Release 11.0
Revision date

SA Bus traffic includes change of value (COV) messages that are issued from inputs located on IOMs/XPMs and commands issued to outputs located on the IOMs/XPMs . Excessive traffic is defined as more than 500 COVs per minute or more than 500 commands per minute.

To resolve communication issues associated with excessive SA Bus traffic, reduce the number of COVs to fewer than 500 per minute and the number of commands to fewer than 500 per minute.

Note: The limit of 500 commands per minute is an approximate maximum that assumes a 1 second token loop time. If your network is configured differently, the actual threshold for this problem may vary. For example, if your token loop time is 2 seconds, the maximum is 240. If you reduce traffic on the SA Bus to 500 and still experience this problem, or you are uncertain of your token loop time, we recommend you reduce command traffic to 240.

To find the number of COVs and commands on your SA Bus, see Inputs and COVs and Outputs and commands. For strategies on reducing traffic on your SA Bus, see SA Bus traffic reduction.