This reports how many modules in this DC group are actively delivering output, the DC-side counterpart to tsiACGroupNbModOK, letting an admin assess active capacity within a specific battery string's set of modules independent of which phase they're wired to. For correlating output health specifically with a shared power source, if a whole DC group's active-module count drops together, the shared battery string or its wiring is a more likely common cause than several coincidental unrelated module failures. An admin seeing a cluster of module failures concentrated in modules sharing the same DC group would investigate that battery string's own health and connections before assuming independent module defects.