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Question for other G11 owners with Onstep and SHC

John Scherer
 

I have some confusion about goto rates between Onstep and the SHC.  I'm sure its just my understanding of how things are working, and maybe other G11 owners with onstep can clear things up.

I've got an older Celestron G11 mount with:
  • Onstep MaxPCB2
  • TMC2130 drivers on RA/DEC with VRef = 0.85v
  • Firmware 2.22p
  • DesiredBaseSlewRate = 1
  • Teensy 3.2 Smart Hand Controller with Firmware 1.5f
  • Orential Motor PKP244MD08B on RA/DEC
  • My Config.MaxPCB.h

My understanding is that with DesiredBaseSlewRate = 1, my maximum slew speed could be anything from .5 deg/s to 2 deg/s, based on how I have the Maximum GOTO speed set in the SHC or the Maximum Slew speed on the MaxPCB2 Wifi Configuration page. Is this correct?

Also, on the SHC, the slew rates displayed in the upper left, based on presses of the Fn buttons:
                   1/4x, 1/2x, 1x, then 2x 1x, 4x 1x, 8x 1x, 20x 1x, 48x 1x, 1/2Mx 1x, Max 1x
These rates are somewhat confusing to me and I assumed these were the same as the Maximum Goto Speed (but more selective?) in the setup menu but I'm not sure.

I ask these questions because my results seem odd to me:

Using the SHC:  Goto Speed (in settings/configuration) set to "Default Speed", if I issue a goto from the SHC, the motors start spinning as expected, but then randomly lock up, only unlocking as the goto action gets closer to the end of the movement and the motor slows down.  Its not until I select a Max Goto Speed = "Slowest", that the motors won't lock up during a slewing action.

The results are somewhat different though if I do a manual slew using N/S/E/W controls.  With the Goto Speed in settings set to "Normal", I can slew manually up to the "1/2Mx 1X" rate, with no motor lockup.

So many options here the behavior is hard to describe but hopefully someone can help.  I'd love to here from others with G11 mounts to see what max goto rates your getting?  I thought I saw that others were seeing around 2 deg/s with similar mount/motors/drivers.

Cheers

John

Redorbit
 

Hi John
I have a fornax51 with the same onstep setup. 
This behaviour may be caused by insufficient cooling of the TMC2130 drivers,so I suppose to measure the temperature of those drivers during gotos.
I added active cooling, since than no problem with stalling/knocking motors
I hope this helps



Regards
Peter


John Scherer <jrsphoto@...> ezt írta (időpont: 2019. nov. 9., Szo, 2:54):

I have some confusion about goto rates between Onstep and the SHC.  I'm sure its just my understanding of how things are working, and maybe other G11 owners with onstep can clear things up.

I've got an older Celestron G11 mount with:
  • Onstep MaxPCB2
  • TMC2130 drivers on RA/DEC with VRef = 0.85v
  • Firmware 2.22p
  • DesiredBaseSlewRate = 1
  • Teensy 3.2 Smart Hand Controller with Firmware 1.5f
  • Orential Motor PKP244MD08B on RA/DEC
  • My Config.MaxPCB.h

My understanding is that with DesiredBaseSlewRate = 1, my maximum slew speed could be anything from .5 deg/s to 2 deg/s, based on how I have the Maximum GOTO speed set in the SHC or the Maximum Slew speed on the MaxPCB2 Wifi Configuration page. Is this correct?

Also, on the SHC, the slew rates displayed in the upper left, based on presses of the Fn buttons:
                   1/4x, 1/2x, 1x, then 2x 1x, 4x 1x, 8x 1x, 20x 1x, 48x 1x, 1/2Mx 1x, Max 1x
These rates are somewhat confusing to me and I assumed these were the same as the Maximum Goto Speed (but more selective?) in the setup menu but I'm not sure.

I ask these questions because my results seem odd to me:

Using the SHC:  Goto Speed (in settings/configuration) set to "Default Speed", if I issue a goto from the SHC, the motors start spinning as expected, but then randomly lock up, only unlocking as the goto action gets closer to the end of the movement and the motor slows down.  Its not until I select a Max Goto Speed = "Slowest", that the motors won't lock up during a slewing action.

The results are somewhat different though if I do a manual slew using N/S/E/W controls.  With the Goto Speed in settings set to "Normal", I can slew manually up to the "1/2Mx 1X" rate, with no motor lockup.

So many options here the behavior is hard to describe but hopefully someone can help.  I'd love to here from others with G11 mounts to see what max goto rates your getting?  I thought I saw that others were seeing around 2 deg/s with similar mount/motors/drivers.

Cheers

John

Howard Dutton
 

Motors are stalling.  I use vref 0.4, higher than that midband resonance causes motors to stall at lesser speeds.  Actually I use 0.85A for tracking stealthChop then drop to 0 4A and switch to spreadCycle (VQUIET) for slews.

Howard Dutton
 

Same behaviour with the little nema11 motors on my mount I use for testing...  about half or a third rated power results in highest slew speeds.

John Scherer
 

Sorry for the delayed reply on this.  I sold this mount to Bryce Brady and was working on making sure the code was the most recent "release" version and in general just making sure things were in order.  He has been in touch with me tonight and says that with the Vref at 0.4v on both RA & DEC, the RA axis is slewing fine, but that the DEC axis is locking up.

Howard Dutton
 
Edited

On Fri, Nov 15, 2019 at 07:52 PM, John Scherer wrote:
Sorry for the delayed reply on this.  I sold this mount to Bryce Brady and was working on making sure the code was the most recent "release" version and in general just making sure things were in order.  He has been in touch with me tonight and says that with the Vref at 0.4v on both RA & DEC, the RA axis is slewing fine, but that the DEC axis is locking up.
There was a bug that crept in a little while back where OnStep would stay in stealthChop during slews for _QUIET mode.  Be sure to update to the latest so that isn't an issue.

I don't have enough information on the exact design and config to comment further other than saying there's lots of OnStep G11's w/NEMA17 directly driving the worms, it's known to work.  I've been using this year and years with various h/w and currently have a MaxPCB2 on my G11 which also works great.