This counts No Request, RPL Blocked (NR-RB) RAPS PDUs received on the west link, the specific message the RPL owner sends to confirm the ring is fully healthy and the RPL is correctly blocked. Seeing this counter actively incrementing on a non-owner node's west link is a positive sign that the RPL owner elsewhere on the ring is healthy and correctly reporting the idle state; a stall in this counter without a corresponding fault alarm can indicate a problem specifically with the RPL owner's own health or PDU transmission rather than this local node. For example, on a stable ring, this counter should increment continuously at the same periodic rate as the plain NR-received counter.