Error handling
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8.3.3 Rx MAC Buffer Overflow / Tx MAC Buffer Underrun
●
Error source
If the Receive MAC buffer of the CN overflows, it cannot receive frames for a
while. The Transmit MAC buffer underrun error on the physical layer occurs; when
the buffer becomes empty during transmission.
●
Error recognition
Whenever a loss of a frame or a timing violation is detected, the CN checks the
Physical Layer for an Rx MAC buffer overflow or a Tx MAC buffer underrun on the
Ethernet MAC controller.
●
Error handling
If a Rx MAC buffer overflow / Tx MAC buffer underrun error is detected, it is logged
as Error code in the StatusResponse frame and transmitted then to the MN. Error
reaction is triggered immediately after detection of the error. The CN NMT state
machine is handle this error source as “Internal Communication Error” (NMT_GT6)
and changes the measuring system state to
NMT_GS_RESET_APPLICATION
.
●
Error signaling
With the inter
nal error function mechanism the error is registered into the “Static
Error Bit Field”. The Static Error Bit Field is part of the StatusResponse frame.
Format:
Byte Offset
Description
1
Content of Object 1001h: ERR_ErrorRegister_U8, 0x01
2
reserved
3-8
Error Code = 0x8166
Table 13: Static Error Bit Field, fragment of the StatusResponse frame
