Software, ASCOM Driver for OnStep


  • Six fixed focuser drivers: independent selections and profiles for focusers 1–6 on OnStepX; legacy OnStep 4.24 supports fixed focusers 1 and 2 only.
  • Two independently registered driver suites: selectable “OnStep” and “OnStep 2” builds, each with its own telescope, focusers, rotator, switch, observing conditions, and saved profiles. Note: most users will install only “OnStep” and skip “OnStep 2”.
  • Safer manual slew release: stop commands bypass preliminary status queries, and rate/start commands stay together.
  • Uncertain movement starts aren’t replayed.
  • Persistent port 9999: enabled for OnStepX 10.29a and later, which requires the matching SWS firmware 2.11b and later.
  • Connection heartbeat: probes after about five seconds without a successful reply. Terminal failures disconnect all clients sharing that session and require explicit reconnection.
  • More resilient TCP communication: handles split and longer replies, bounded retries, and per-device timeouts.
  • Improved cleanup and recovery: failed initialization, disposal, and abandoned client connections release their resources. Stale clients cannot interfere with a replacement session.