Raw Data Sequence Number Error on Inverter Board

When error [5.7021] occurs, the robot stops in SS1 stop mode, decelerating and then switching to STO.

• The error is raised when you try to turn the servo on, and the servo does not turn on.
• The robot stops during normal operation, often together with 4.1023, 5.7023 or 5.7024.
• Param 2 shows which inverter (joint) the error came from.

[5.7021] Safety controller category

Raw data sequence number error occurred on Inverter board.
Param 1: CPU Number
Param 2: Inverter Number

The joints in the robot arm send their data to the controller with a sequence number that increases by one on every packet. This error means a packet arrived out of sequence — data was lost or delayed on the way.

• Communication cable — the most common. Poor contact or damage in the cable between the controller and the robot arm.
• Program overloading the controller — a while, repeat or thread block that runs commands with no wait keeps the controller busy, and data is dropped.
• Accumulated logs — the error appears immediately after servo on and task start.
• Noise or grounding — the cable runs next to a high-current line or a strong noise source, or the installation is poorly grounded.
• A part in the robot arm — this needs service.

• Record the condition, then turn the system off and on.
• With the power off, disconnect and reconnect the robot arm cable at the controller rather than only looking at it. Check the connector pins and the cable along its length.
• Check that the cable does not run alongside a high-voltage or high-current line (for example a welding cable), and that the installation is properly grounded.
• If a while, repeat or thread block in the program runs with no delay, add a wait inside the loop. From V2.11.1 the repeat block also has a wait time setting.
• If the error appears immediately after servo on and task start, turn the power off and on, then try again.

If the error continues, contact your distributor. See also [DART-Studio] Trouble Shooting Guide.

• Robot model and serial number
• Software version of the controller
• The error code with its Param values, all codes shown with it, and the date and time
• Whether it happens at servo on or during operation
• The controller log exported right after the error

• 4.1023 Communication Error-Heart Beat
• 5.7023 Joint torque sensor data sequence number error occurred on Inverter board
• 5.7024 Joint torque sensor data CRC32 check failed on Inverter board
• 5.7025 Motion Controller data sequence number error occurred
• 5.7073 Joint position control error