8.5.1.3.4.1 Byte Errors

General byte errors (COMM_*_R*_FAULT[BERR]) and initialization byte errors (COMM_*_RC_FAULT[IERR]) are the result of improper formatting of a byte. When these occur, the assumption is that the frame timing is incorrect and the information must not be used. Therefore, when a general byte error occurs, all bytes that follow are ignored until a communication break (for UART interface) or start-of-frame bit set (daisy chain interface) is received. As a result, these errors utilize special handling and must be cleared using a communication clear or reset.

COMM_COM*_R*_FAULT[BERR] is set when a byte error occurs on any byte in a frame received on the COMH/COML interface. The COMM_UART_R*_FAULT[BERR] bit is set when a STOP error occurs on any byte received on the UART interface that is not directly followed by a communication clear. When the byte error occurs, all further bytes received on that interface are ignored. Bytes received on COMH/COML are propagated up the stack, while bytes received on the UART are not propagated. Any other frame errors that occur while the bytes are ignored are not realized or indicated as they are ignored. This includes CRC errors. The bytes are ignored until a SOF byte (COMH/COML) or communication clear (UART interface) is received.

The COMM_COM*_RC_FAULT[IERR] bit is set when a frame initialization byte is expected, but the SOF bit of the received byte is not set or an invalid frame type (one of the reserved commands) is selected. The COMM_UART_RC_FAULT[IERR] bit is set when the frame initialization byte has a stop error, reserved command bits set, or is configured as a response frame (not in multidrop mode). Frame initialization bytes for UART are the 1st byte after a break, or based on frame sequence. When in the multidrop configuration, IERR is also set when the first frame received after a break is a response frame. Bytes received on COMH/COML are propagated up the stack so it is likely all devices in the stack will indicate the IERR fault, bytes received on the UART are not propagated. Any other frame errors that occur while the bytes are ignored are not realized or indicated as they are ignored. This includes CRC errors. The bytes are ignored until a SOF byte (COMH/COML) or communication clear (UART interface) is received.