Issue
What process do the bCX and b3 controllers use to automatically establish their communication bus speed.
Product Line
Andover Continuum
Environment
- bCX
- b3
- Auto Baud
- MSTP
Cause
Having issues with b3 controllers selecting the wrong bus speed.
Resolution
The process by which the b3 controllers establish their communication speed is as follows.
- When the b3 controllers power up, they listen to the network for 2.5 seconds
- If they hear communication at their last known Baud rate, they start talking when they hear the poll for master.
- If they hear no communication after 2.5 seconds, they start their own poll for master at their last known Baud Rate.
- If they hear garbled communication during the 2.5 second listen mode, they begin hunting different Baud Rates while listening until they have synced to the Baud Rate they are listening to.
- Then they join the token passing when they receive the Poll for Master.
Note: There was a issue with the autobaud process in earlier versions of the b3 and BCX40xx controllers which would cause them to set the communication speed incorrectly. This issue was corrected in the following firmware versions.
- BCX40xx ==> 4.500053
- b3xxx ==> 4.500064
- b-3xxx-V ==> 4.501064
