bb is Base Block or shutting off the signal to the output transistors.

bb is not a fault but rather a condition signifying power has been blocked from the base (main power circuit) of the servo.

The following conditions must be met or the servo will be placed in bb (Base Block) condition:

1. S-ON (Servo ON) signal must be enabled.
2. Main circuit power must be ON. It can be single or three phase. Verify CHARGE light on the drive. It should be lit solid, not dim.
3. Check if SEN signal is ON when absolute encoder is used. SEN signal is required when absolute encoder is used for Analog and Pulse Train reference type of servopacks.
   Note: To disable the required SEN signal, it can be disabled by setting PN002.2 = 1 (use absolute encoder as an incremental) which requires Homing at every start
4. In some applications (Sigma-2, Sigma-3 and Sigma 5), the motor has an absolute encoder but being operated as an incremental encoder. In these applications, parameter Pn002.2 must be set = 1.
5. When using the Hbb (Hardware Base Block) input circuit, the Hbb circuit on CN8 must be closed or the jumper plug on CN8 must be installed for Sigma 5.
6. When the servo is used with a Yaskawa motion controller, some motion controller conditions may force the servo into a bb condition. In these cases, check the controller sequence. Use utility function Fn002 after disconnecting the controller to verify that the servo ON signal jogs the motor.