Introduction

BackChannel Diagnosis is performed on the TimingMaster node. It inspects the ring segment by segment until it finds a ring break or detects a closed ring.

It cannot be performed during Node Discovery or Programming service.

Operation

Calling Ucs_Bcd_Start() starts the BackChannel Diagnosis. The function has a parameter report_fptr. It points to the report callback function. report_fptr will deliver a result for each inspected segment as well as a result which indicates the end of the diagnosis session.

Segment number 0 denotes the segment following the TimingMaster.

Parameter code	Parameter segment	Description
UCS_BCD_RES_SUCCESS	segment number	current segment is not broken
UCS_BCD_RES_NO_RING_BREAK	segment number	No ring break detected. segment = number of nodes - 1.
UCS_BCD_RES_RING_BREAK	segment number	Ring break detected in current segment.
UCS_BCD_RES_TIMEOUT1	segment number	Error during diagnosis: no communication on back channel.
UCS_BCD_RES_TIMEOUT2	UCS_BCD_DUMMY_SEGMENT	Error during diagnosis: no result received from local INIC.
UCS_BCD_RES_ERROR	UCS_BCD_DUMMY_SEGMENT	An unexcpected error occurred. BackChannel Diagnosis was stopped.
UCS_BCD_RES_END	UCS_BCD_DUMMY_SEGMENT	BackChannel Diagnosis ended regularly.