Group not ready / group not ready for new task

What does 4220 mean?

The NC group received a new motion task while it was still actively processing a previous task. This request is rejected to prevent interruption of the existing task and maintain motion integrity. Attempting to force a new task can lead to unpredictable motion, collisions, or data inconsistencies.

• Attempting to start a new motion command on a group before the previous command has fully completed (e.g., sending G01 before G00 finishes).
• Insufficient PLC handshake logic to confirm motion completion (e.g., not waiting for 'MotionDone' flag from NC).
• Rapid succession of motion commands from an external HMI or PLC without proper sequencing or task queuing.
• Excessively long motion profiles or complex interpolated movements delaying actual group readiness.
• Firmware bug causing delayed status updates for group readiness signals to external systems.

Click steps to track your progress.

1. 1

   1. Modify the NC program or PLC logic to ensure each motion command completes before the next one is issued (e.g., poll 'Group[n].State == IDLE').

2. 2

   2. Implement a delay or handshake signal (e.g., using a 'MotionComplete' PLC bit) to synchronize new motion tasks.

3. 3

   3. Verify the NC group's status in the diagnostics (e.g., 'Group[n].CurrentTask' or 'Group[n].Status') before issuing new commands.

4. 4

   4. Review the NC program for unintended rapid command execution, especially during nested subroutines or loops.

5. 5

   5. Optimize motion profiles by checking acceleration/deceleration parameters (e.g., P6-10 'AccTime', P6-11 'DecTime') to ensure timely completion.