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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, SWS 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 always adhered to during guides since guiding is used to move the mount back within limits to restore operation.  When guiding and a limit is exceeded the guide will be stopped IF tracking is enabled.  Afterwards you can still start another guide to move back in limits (or further out if you don't watch what you're doing) and turn tracking back on to recover.  In some cases, where the direction that broke the limit is readily known, only guides in the correct direction will then be allowed.

Finally min, max, meridian, overhead, and horizon limits are disabled until normal operation is started (for example unparking or starting an align.)  This is to allow freedom to use guides to position the optical tube in the home orientation (mostly for large 'scopes or those without clutches.)

  • 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 and/or accessible from SWS Website Config page:)
    • Notes:
      • AXISn_LIMIT_MIN
      • AXISn_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 (GPS, RTC) 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 via a TLS or other means if the geographic location changes.
  • LONGITUDE:
    • Mount Type:  All
    • Default Value:  0
    • Other Values-180 to 180 (degrees)
    • Reminder:  Must be set via a TLS or other means if the geographic location changes.
  • UTC OFFSET:
    • Mount Type:  GEM, FORK
    • Default Value:  7
    • Other Values-12 to 14 (hours)
    • Reminder:
      • Should be set via a TLS or other means if the geographic location changes.
      • In OnStep it is assumed that this value is appropriate for Standard Time, NOT Daylight Time.  Given this method of operation there is no need to change the UTC Offset with changes due to Daylight Time being in effect.
  • OTHER (NON-RUNTIME:)
    • Notes:
      • TIME_LOCATION_SOURCE
    • Reminder: See Config.h and Configuration.

Rotator

To allow compensating for backlash (slop in gears, etc.) causing a shift in the rotator position the following can be configured. 

  • BACKLASH:
    • Mount Type:  All
    • Default Value:  0
    • Other Values0 to 32767 (steps)
    • Notes Value.
    • Reminder:  A setting of 0 disables this feature.
  • OTHER (NON-RUNTIME:)

Focusers

To allow compensating for backlash (slop in gears, etc.) and temperature related expansion/contraction causing a shift in the focus position the following can be configured. 

  • BACKLASH:
    • Mount Type:  All
    • Default Value:  0
    • Other Values0 to 32767 (steps)
    • Notes Value.
    • Reminder:
      • A setting of 0 disables this feature.
      • Not supported for DC motor focusers.
  • TEMPERATURE COMPENSATED FOCUSING (TCF,) COEFFICIENT:
    • Mount Type:  All
    • Default Value:  0.0
    • Other Values-999.9 to 999.9 (microns per deg. C)
    • Notes A positive value moves focus out as temperature drops.
    • Reminder:
      • The temperature comes from Config.h TELESCOPE_TEMPERATURE if enabled.  If not enabled it falls back to the ambient temperature from WEATHER.
      • Not supported for DC motor focusers.
  • TEMPERATURE COMPENSATED FOCUSING (TCF,) DEADBAND:
    • Mount Type:  All
    • Default Value:  1
    • Other Values1 to 32767 (steps)
    • Notes Represents how far the position is allowed to change due to TCF before an action to move the focuser occurs.
    • Reminder:
      • This helps with imaging by limiting how often focuser movement occurs. 
      • Not supported for DC motor focusers.
  • TEMPERATURE COMPENSATED FOCUSING (TCF,) ENABLE:
    • Mount Type:  All
    • Default Value:  0
    • Other Values0 to 1 (off/on)
    • Notes Disables or enables TCF.
    • Reminder:  Not supported for DC motor focusers.
  • OTHER (NON-RUNTIME:)