Daisy-chain communication bus and protocol

An apparatus is provided that includes first and second connection nodes and a communication circuit. The communication circuit is configured to communicate cell-status data of a cell over a bidirectional data path connected to the connection nodes. The communication circuit includes directional drive circuitry configured to communicate the cell-status data over the bi-directional data path by communicating the cell-status data via the first connection node to first-side circuitry in the one direction of the bi-directional data path and, in response to an indication that the bi-directional data path is faulty, by communicating via the second connection node to second-side circuitry along the other direction of the bi-directional data path. The communication circuit also includes a communication-protocol circuit configured to control the directional drive circuitry. The apparatus may be connected in-series with other like apparatuses in the bi-directional data path.