Maximizing tips - Metasys - LIT-12011034 - General System Information - Metasys System - Release 11.0

MS/TP Communications Bus Technical Bulletin

Brand
Metasys
Product name
Metasys System
Document type
Technical Bulletin
Document number
LIT-12011034
Version
Release 11.0
Revision date
2022-02-07
Language
English

Observe the following guidelines to maximize the performance of an MS/TP bus.

Guideline

Description

Limit the number of Change of Value (COV) report rates over the MS/TP Bus

COV reports account for the highest amount of traffic on the bus. For best performance, keep the COV rate at 500 COVs per minute or fewer for each network. To reduce the COV traffic:

  • Set the COV increment to the largest value that still provides acceptable performance.
  • Do not map more points to the NxE than are required.

For mapped analog points, where the values are changing frequently, consider the following to limit COV reports:

  • Increase the COV increment on the point.
Note: For some Analog Inputs (AIs), this value cannot be modified.
  • Set the Use Cov Min Send Time flag to true, which causes the COVs to be sent on a timed basis. The time value is specified in the controller device object.

Do not place subordinate devices on the FC Bus

Subordinate devices on the FC bus are not supported. The SA bus only supports a specific set of subordinate devices.

Carefully evaluate third-party devices

Third-party devices can seriously degrade both hardware and software performance depending on their quality and configuration. Consider and configure third-party devices carefully according to the manufacturer’s specifications.

Do not add extra traffic

Once the system is configured, commissioned, and running, avoid adding extra traffic to the bus by performing unnecessary auto-discovery operations, downloads, or bus analysis.

Observe the MS/TP wiring guidelines

Follow the wiring rules carefully. The tolerances of the MS/TP bus are tighter than other, slower protocols may be. Improper terminations may result in errors causing serious network degradation. See MS/TP Bus cable recommendations.

Check the MS/TP statistics for errors

See Statistics attributes.

Use default MS/TP settings

Avoid changing default MS/TP bus settings, especially settings you may be unfamiliar with. Some parameters set improperly or randomly can cripple the MS/TP bus completely.