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Run-time Configuration

It's a good idea to also configure some run-time settings to tailor OnStep's behavior to your mount.  These settings are available in the Android App, Website, and SHC.  Several are also available in the ASCOM driver's configuration dialog.


Slew Speed

These options allow adjusting the goto/slew speed in OnStep from 1/2 to 2x the SLEW_RATE_BASE_DESIRED (possible limited by OnStep) set in Config.h.

  • MAXIMUM SLEW SPEED:
    • Mount Type:  ALL
    • Default Value:  NORMAL (1x)
    • Other ValuesVSLOW (0.5x), SLOW (0.75x), NORMAL (1x), FAST (1.5x), VFAST (2x)
  • OTHER (NON-RUNTIME:)
    • Notes:
      • SLEW_RATE_BASE_DESIRED
    • Reminder: See Config.h and Configuration.

Backlash

Backlash compensation is used to improve pointing accuracy and (in some cases) guiding responsiveness by allowing for the slack (or space) between teeth in the gear train.  The procedure for adjusting backlash is here.

  • RA/AZM:
    • Mount Type:  ALL
    • Default Value:  0
    • Other Values0 to 3600 (arc-seconds)
  • DEC/ALT:
    • Mount Type:  ALL
    • Default Value:  0
    • Other Values0 to 3600 (arc-seconds)
  • OTHER (NON-RUNTIME:)
    • Notes:
      • GUIDE_TIME_LIMIT
      • GUIDE_DISABLE_BACKLASH
    • Reminder:

Limits

During tracking and gotos if a limit is broken motion is stopped by canceling any goto and turning tracking off.  Keep in mind that up to SLEW_RAPID_STOP_DIST (Config.h) distance should be allowed for to stop the motors/mount once the limit is detected.  Limits are not adhered to during guide commands (with the exception of Dec on mounts with a Tangent Arm) since guiding is used to move the mount back within limits to restore operation (allowing you to re-enable tracking and continue operation.)

  • OVERHEAD:
    • Mount Type:  All
    • Default Value:  80
    • Other Values60 to 90 (degrees)
    • Notes Blocks telescope motion near the Zenith.
    • Reminder:  A setting of 90 disables this feature.
  • HORIZON:
    • Mount Type:  All
    • Default Value:  -10
    • Other Values-30 to 30 (degrees)
    • Notes Blocks telescope motion near the Horizon.
    • Reminder:  OnStep has slewing features that reduce the likelihood of inadvertently dropping below the horizon limit during gotos.
  • MERIDIAN EAST:
    • Mount Type:  GEM, FORK
    • Default Value:  7
    • Other Values-180 to 180 (degrees)
    • Notes Allowed distance past the Meridian (+) when telescope is East of the pier (triggers a Meridian Flip.)
    • Reminder:  Using a (-) value excludes areas before the Meridian.
  • MERIDIAN WEST:
    • Mount Type:  GEM, FORK
    • Default Value:  7
    • Other Values-180 to 180 (degrees)
    • Notes Allowed distance past the Meridian (+) when telescope is West of the pier (triggers a Meridian Flip or stops Tracking.)
    • Reminder:  Using a (-) value excludes areas before the Meridian.
  • OTHER (NON-RUNTIME:)
    • Notes:
      • AXIS1_LIMIT_UNDER_POLE
      • AXIS1_LIMIT_MAXAZM
      • AXIS2_LIMIT_MIN
      • AXIS2_LIMIT_MAX
      • LIMIT_SENSE_ON
    • Reminder: See Config.h and Configuration.

Site Information

OnStep must know where it's located and what the date/time is to predict where the RA/Dec and Alt/Azm coordinates are in the Sky.  This information is sometimes set automatically (though possibly partially) by a TLS (Time Location Source.)  With a GPS TLS you just need to have the UTC Offset correct.  With an RTC TLS DS3231 (etc.) supplying the Date/Time you need to have the Latitude, Longitude, and UTC Offset correct.  Otherwise you must be sure all of these are set properly at startup; though OnStep will remember your prior session values which is often useful.

  • DATE/TIME:
    • Mount Type:  All
    • Notes Most OnStep Applications/Drivers indirectly (but effectively) set OnStep's internal Universal Time so the UTC Offset being correct or not doesn't matter except for the users purposes.
    • Reminder:  Must be set via a TLS or other means.  OnStep has some internal flags so that the SHC can detect if the date/time is set and asks for it if needed.
  • LATITUDE:
    • Mount Type:  All
    • Default Value:  0
    • Other Values-90 to 90 (degrees)
    • ReminderMust be set if the geographic location changes via a TLS or other means.
  • LONGITUDE:
    • Mount Type:  All
    • Default Value:  0
    • Other Values-180 to 180 (degrees)
    • Reminder:  Must be set if the geographic location changes via a TLS or other means.
  • UTC OFFSET:
    • Mount Type:  GEM, FORK
    • Default Value:  7
    • Other Values-12 to 14 (hours)
    • Reminder Must be set if the geographic location changes via a TLS or other means.
  • OTHER (NON-RUNTIME:)
    • Notes:
      • TIME_LOCATION_SOURCE
    • Reminder: See Config.h and Configuration.