The FAST Error Notification and SLOW Error Notification of SENT have reported no faults.
You can read the data recorded in "bitchange.xlsx" for analysis, as it contains information on the 2 and 3 bits of each status half-word of the fast channel that I have recorded. Bit1 and Bit0 information are discarded because they have no meaning in the slow channel.
At the same time, I have manually parsed the slow channel information and identified it with black squares.
In "bitchange.xlsx", the data in the "State" row corresponds to "Flexio_Sent_Ip_axFastData[Instance][ChannelId].SerialState" in the code. This is responsible for detecting and identifying whether the slow channel is "Short" or "Enhanced". The "count" represents "Flexio_Sent_Ip_axFastData[Instance][ChannelId].FastMsgCount", which is responsible for counting the receive length of the slow channel.
I believe the reason we are not receiving any Slow Channel data is that the code cannot correctly identify whether the slow channel is "Short" or "Enhanced". You can read "bitchange.xlsx" to discover that the identification state is constantly jumping between "STATUS_SENT_SERIAL_IDLE", "STATUS_SENT_SERIAL_SHORT", and "STATUS_SENT_SERIAL_ENHANCED".

When the identification state transitions, the "Flexio_Sent_Ip_ProcessSerialMsg()" function returns "STATUS_FLEXIO_SENT_IP_ERROR", but this return value is only resetting SerialState and FastMsgCount in the upper-level function "Flexio_Sent_Ip_DmaDataProcessing()", and it does not call SentFastErrorNotif(). Therefore, I cannot obtain any error information through the fast Error Notification.
In “bitChange.xlsx”

We can start from column T, at this time SerialState = STATUS_SENT_SERIAL_IDLE, FastMsgCount = 0.
When we receive column U, Flexio_Sent_Ip_ProcessSerialMsg() believes bit3 == 1, so it considers this a start signal for slow channel and sets SerialState = STATUS_SENT_SERIAL_SHORT and FastMsgCount = 1.
When we receive column V,Flexio_Sent_Ip_ProcessSerialMsg() believes bit3 == 0, so it keeps SerialState = STATUS_SENT_SERIAL_SHORT and increments FastMsgCount = 2.
When we receive column W, Flexio_Sent_Ip_ProcessSerialMsg() believes bit3 == 1. At this point, since FastMsgCount == 2, it does not meet the condition to jump to STATUS_SENT_SERIAL_ENHANCED, and can only return STATUS_FLEXIO_SENT_IP_ERROR. In Flexio_Sent_Ip_DmaDataProcessing(), it resets SerialState and FastMsgCount.
By the way, I am using DMA to receive SENT data, and I have only confirmed that there is an issue with the DMA reception method. At present, I cannot confirm whether the interrupt and polling methods also have the same problem.