The RESPONSE packets to NWRITE_R packets may be dropped by the I/O Write Master within the RapidIO® MegaCore® function when there is insufficient bandwidth on the Transport Layer to transport the required RESPONSE packets.
A round-robin arbitration scheme is used to grant access to the Transport Layer between the Avalon-ST Pass-Through Interface, Doorbell, I/O Slave, I/O Master and Maintenance ports. If another interface (e.g. I/O Slave) is transmitting packets, the RESPONSE egress rate from the I/O Master may be lower than the NWRITE_R ingress rate, which will lead to the RESPONSE being dropped. When a RESPONSE to an NWRITE_R is dropped, the PKT_RSP_TIMEOUT bit of the Logical/Transport Layer Error Detect CSR in the device that transmitted the NWRITE_R is asserted.