Fast CAN Queue (unbuffered)

Received messages are no longer buffered on the EL6751. The RxQueue should therefore be large enough for all messages theoretically receivable within an EtherCAT cycle to fit inside.

The received messages no longer have to be confirmed. The EL6751 increments the RxCounter when new messages are received.

In the transmission direction too, only the data dependent on the changed TxCounter and the NoOfTxMessages are copied, so that the number of parallel messages in the queue actually have no further influence on the runtime (only the NoOfTxMessages).

Since the EL6751 operates in 3-buffer mode (so that it always has a buffer in which it can copy the CAN messages received), it may be the case that the unused messages contain incorrect or old data.

The object directory can be read on the CoE-Online tab. If the index 0x1C32:08 has been/is set to 1, the local cycle time of the EL6751 is measured and stored in index 0x1C32:05 (maximum value). You can thus see whether the EL6751 will be finished within the EtherCAT cycle.

The Fast CAN Queue may not contain further CANopen or CAN-Layer-2 nodes.