SA Bus Diagnostics - Johnson Controls - Metasys - LIT-12011147 - Software Application - Controller Configuration Tool - 13.1

Controller Tool Help

Brand
Johnson Controls
Metasys
Product name
Controller Configuration Tool
Document type
User Guide
Document number
LIT-12011147
Version
13.1
Revision date
2019-12-04
Language
English

The SA Bus Performance attribute, which is located on the Device Information Screen, indicates the current performance of the bus, such as low, medium, or high. Values of COV Receive Rates and Average Token Loop times are indicators of SA bus performance. See the following table.

Table 1. SA Bus Performance Levels
SA Bus Performance Description
LOW Average COV Receive Rate greater than 600, OR Average Token Loop greater than 2,000 ms.
MEDIUM Average COV Receive Rate greater than 300 and less than or equal to 600, OR Average Token Loop greater than 1,000 ms and less than or equal to 2,000 ms.
HIGH Average COV Receive Rate less than or equal to 300, AND Average Token Loop less than or equal to 1,000 ms.
NOT APPLICABLE Indicates unsupported data type, such as Ethernet.

Maximum traffic over control networks is mostly due to noisy analog signals. In the event you are experiencing low or medium bus performance, try increasing the update interval time of the AI points on your Point Expansion Modules. AI points on SA Bus devices periodically send COV messages back to the controller regardless of a change in value. This guarantees closed loop application control, but also increases periodic traffic on the bus.