ovrTrans Queue

What does x240 mean?

The transmit request memory has overflowed, indicating too many CAN objects are queued for transmission. This can lead to delays or loss of communication on the system bus.

• PLC program is attempting to send CAN messages at a rate exceeding the controller's transmit buffer capacity (e.g., `CAN_Send_PDO` called too frequently).
• A faulty CAN slave device on the bus (e.g., `Node_ID_5`) is not acknowledging messages, causing the master's transmit queue to back up.
• Insufficient CAN bus bandwidth for the number of messages and data volume being transmitted, leading to congestion.
• High-priority tasks generating frequent CAN transmit requests, saturating the queue and delaying lower-priority messages.
• Incorrect configuration of the CAN transmit buffer size (e.g., `CANCfg_TxBufferSize` parameter) in the controller, making it too small.

Click steps to track your progress.

1. 1

   1. Review the PLC program logic to identify all CAN transmit commands (e.g., `CAN_Send_PDO`, `CAN_Transmit`) and reduce their frequency or data size if possible.

2. 2

   2. Monitor the CAN bus load using a CAN analyzer tool (e.g., Peak-CAN) connected to the bus to identify message bursts or excessively chatty nodes.

3. 3

   3. Verify the status and operation of all CAN slave devices on the bus (e.g., `Node_ID_5_Status`) to ensure they are online and acknowledging messages correctly.

4. 4

   4. Adjust the CAN bus baud rate (e.g., `CANCfg_BaudRate` parameter in `P8-01`) to a higher speed if the physical bus and devices support it, increasing bandwidth.

5. 5

   5. Increase the CAN transmit buffer size in the controller's configuration (e.g., `CANCfg_TxQueueDepth`) if hardware resources allow, providing more buffer capacity.