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Re: PMC-Eight Rate Offset Value in ASCOM driver setup is probably not correct for your mount

hubbell_jerry@...
 

Hi Bob,

I actually just wrote a knowledge base article about this and posted it here:


You can do a pretty good estimate if you were to use a cross-hair eyepiece and do the following procedure

Note: In the following measurement, you should have a way to record the RA value in decimal arc-seconds to a precision of at least 0.1 seconds in RA. Cartes du Ciel provides in the telescope connections dialog box.

1. Center a bright star in your scope right past the Meridian (RA coordinate a few minutes earlier than your     local Sidereal Time) and near 0 deg Declination.

2. Note the time you centered the star.

3. Note the RA coordinates your ASCOM application shows where you are pointed.

4. Wait at least 20 minutes.

5. Move your mount using the POTH or equivalent in RA to recenter the star in your eyepiece.

6. Repeat steps 2 and 3.

7. Calculate the difference in RA coordinates in Seconds

8. Calculate the elapsed time between the times recorded in step 2 and 6.

9. Multiply the value determined in step 7 by 15, i.e., 3.2 (sec) x 15 (arc-sec/sec)  = 48 (arc-sec).

10. Divide the value determined in step 9 (drift arc-sec) by the value determined in step 8 (elapsed time). This is the Rate Offset Value.

11. Determine the sign of the Rate Offset Value determined in step 10 by noting if the RA coordinate recorded in step 3 is "earlier" or "later" than that RA coordinate recorded in step 6. If the value in step 3 is "earlier" then the sign of the tracking is FAST and the offset should be NEGATIVE. If the value in step 3 is "later" then the sign of the tracking is SLOW and the offset should be POSITIVE.

This may seem a bit complex, but this is how it should be done.

I will add this procedure to the knowledge base article.

Thanks.

Jerry Hubbell
Director Electrical Engineering
Explore Scientific, LLC.


Re: PMC-Eight Rate Offset Value in ASCOM driver setup is probably not correct for your mount

Robert Hoskin <r_hoskin@...>
 

Oh!   Thanks for this!

What do you think the root cause of the variance is?  Gear tolerances?

Any idea how this applies to EXOS2 vs Losmandy mounts, and how someone who's not guiding might determine a correct value for their mount?  
[In other news,I see my mount head is being shipped back now, so I'll be back to figuring out its limits soon.  Good to know this, ahead of that.]


From: "hubbell_jerry@... [ESPMC-Eight]"
To: ESPMC-Eight@...
Sent: Thursday, June 14, 2018 10:34 AM
Subject: [ESPMC-Eight] PMC-Eight Rate Offset Value in ASCOM driver setup is probably not correct for your mount

 
The latest version of the PMC-Eight ASCOM driver has a parameter called Rate Offset under the Miscellaneous tab on the driver setup dialog box. I have set the default value of this parameter to 0.023 Arc-sec/sec based on the testing I performed on the PMC-Eight when developing this adjustment parameter. 

The purpose of this parameter is to allow you to finely tune your tracking rate to correct for any small error in your RA tracking when NOT USING and autoguider system. This only becomes an issue if you are doing astrophotography without auto-guiding which many beginning astrophotographers do.

The value of 0.023 Arc-Sec/Sec set may not be valid for your system. The problem was discovered when Ji Theriot was providing me PE data for his mount using PHD2. He provided me 30 minutes worth of tracking data without correcting the mount using PHD2 to allow me to analyse his mount's native PE. At that time his data showed that his RA tracking was drifting about 80 arc-seconds over a 30 minute period, which was equal to a drift rate of -0.044 Arc-Sec/Sec. 

The default offset value was not correct for his PMC-Eight. 

After some testing, he discovered that a Rate Offset value of -0.0135 was needed for his mount to properly track.He said that after doing this the mount tracks near perfectly.

I recommend that you set your Rate Offset value to 0.000 until you can test your mount's tracking rate using an auto-guiding system and PHD2 to measure the precise tracking rate error. Please let me know if you have any questions about this.

The next release of the PMC-Eight ASCOM driver will have the default for the Rate Offset Value set to 0.000.

Ji may chime in here about his experience and how he went about adjusting his Rate Offset Value.

Thanks

Jerry Hubbell
Director Electrical Engineering
Explore Scientific, LLC.






PMC-Eight Rate Offset Value in ASCOM driver setup is probably not correct for your mount

hubbell_jerry@...
 

The latest version of the PMC-Eight ASCOM driver has a parameter called Rate Offset under the Miscellaneous tab on the driver setup dialog box. I have set the default value of this parameter to 0.023 Arc-sec/sec based on the testing I performed on the PMC-Eight when developing this adjustment parameter. 


The purpose of this parameter is to allow you to finely tune your tracking rate to correct for any small error in your RA tracking when NOT USING and autoguider system. This only becomes an issue if you are doing astrophotography without auto-guiding which many beginning astrophotographers do.


The value of 0.023 Arc-Sec/Sec set may not be valid for your system. The problem was discovered when Ji Theriot was providing me PE data for his mount using PHD2. He provided me 30 minutes worth of tracking data without correcting the mount using PHD2 to allow me to analyse his mount's native PE. At that time his data showed that his RA tracking was drifting about 80 arc-seconds over a 30 minute period, which was equal to a drift rate of -0.044 Arc-Sec/Sec. 


The default offset value was not correct for his PMC-Eight. 


After some testing, he discovered that a Rate Offset value of -0.0135 was needed for his mount to properly track.He said that after doing this the mount tracks near perfectly.


I recommend that you set your Rate Offset value to 0.000 until you can test your mount's tracking rate using an auto-guiding system and PHD2 to measure the precise tracking rate error. Please let me know if you have any questions about this.


The next release of the PMC-Eight ASCOM driver will have the default for the Rate Offset Value set to 0.000.


Ji may chime in here about his experience and how he went about adjusting his Rate Offset Value.


Thanks


Jerry Hubbell

Director Electrical Engineering

Explore Scientific, LLC.





Re: ASCOMPAD and PMC-8 Connection Problems

W. Christopher Moses
 

I seem to remember that my QHY5L-II-M was pretty finicky also.  I'll be home in a few days and will check my notes to see if I have any info that might help you.

On Tuesday, June 12, 2018, 11:16:49 AM PDT, lamb_mark@... [ESPMC-Eight] wrote:


 

My PMC-8 has remained in the serial mode the last few times I have used it in the past week; each time having been totally powered down in between.  I have no idea why it was automatically reverting to wifi after power down the previous couple of times???  I will keep it in serial connect mode, though in the interim wifi had worked flawlessly for two nights last week, with the tablet ~3ft from PMC-8.  My previous wifi problems could have been caused by my tablet being 1-2ft away???


My ASCOMPAD continues requires the window to be visible and being "clicked" on for my XBox controller to move the mount, however.  PITA

I still have not done any PHD2 guiding, as PHD2 was NOT getting exposures from my QHY5L-II-M.  Yesterday, I played with PHD2 in my basement, and I still had some connectivity problems, but I was finally able to get the camera to work connecting it as "QHY Camera".  For some reason, connecting as QHY5L-II (???) would not work.  Hopefully, PHD2 will work the next time I have good weather.




 


Re: ASCOMPAD and PMC-8 Connection Problems

hubbell_jerry@...
 

Hi Mark,

That's good to hear that your PMC-Eight is behaving itself now. That really is a strange problem. I'm sorry I can't help you with the ASCOMPAD issue as I don't really have any time to investigate it. I think you said you posted the issue on the EQMOD group, but didn't get any good response there. All I can suggest is to maybe try it again.

Thanks for they update!

Jerry Hubbell
Director Electrical Engineering 
Explore Scientific, LLC.


What to do if you have a problem with your G11 mount while Auto-Guiding

hubbell_jerry@...
 

I have just posted an article talking about what you should do if you identify an issue with your mount's auto-guiding and/or periodic error. The article includes instructions on how to report any issue you may have to Explore Scientific Customer Service.


http://hosted.comm100.com/KnowledgeBase/My-ES-Losmandy-G11-mount-s-periodic-error-(PE)-is-higher-than-I-expect,-what-can-I-do-to-Improve-that-_A5000032.aspx?id=5000032&siteid=56501


Jerry Hubbell

Director Electrical Engineering

Explore Scientific, LLC.


Re: ASCOMPAD and PMC-8 Connection Problems

Mark Lamb
 

My PMC-8 has remained in the serial mode the last few times I have used it in the past week; each time having been totally powered down in between.  I have no idea why it was automatically reverting to wifi after power down the previous couple of times???  I will keep it in serial connect mode, though in the interim wifi had worked flawlessly for two nights last week, with the tablet ~3ft from PMC-8.  My previous wifi problems could have been caused by my tablet being 1-2ft away???

My ASCOMPAD continues requires the window to be visible and being "clicked" on for my XBox controller to move the mount, however.  PITA

I still have not done any PHD2 guiding, as PHD2 was NOT getting exposures from my QHY5L-II-M.  Yesterday, I played with PHD2 in my basement, and I still had some connectivity problems, but I was finally able to get the camera to work connecting it as "QHY Camera".  For some reason, connecting as QHY5L-II (???) would not work.  Hopefully, PHD2 will work the next time I have good weather.




 


Re: Exos-2 PMC-8 - pier extension & axes stabilty

Jennifer Shelly
 

Thanks Steve I will check it out.


Re: Exos-2 PMC-8 - pier extension & axes stabilty

Jennifer Shelly
 

Thanks Bob. I will definitely contact ES.


Re: Exos-2 PMC-8 - pier extension & axes stabilty

r_hoskin@...
 

Jennifer,

I have an EXOS-2/PMC-8, too.  If the clutches are locked, the wobble you are feeling will be the play between the worm and ring gears on each axis.  The two sets of teeth have either moved apart in use (the worm gear clearance is adjustable), or they left the factory like that.

My own mount arrived with very little play on either axis, but after some use, the RA loosened up. If you contact ES customer service, they can send you instructions on making the adjustment.  This problem recurred on mine after adjustment, and it is currently in Springdale (at ES's request!), undergoing what I fervently hope is a rejuvenation.  YMMV.

There is always going to be some imperfection in the way the ring and the worm interact on this design of mount, so some play will come with the territory.  If it's more than you're comfortable with, you can either adjust it yourself (ES can provide instructions, and Google is your friend), or you can ask ES if they'll do that for you. 

I think the key thing is whether the amout of play you're experiencing is stable, or increasing.  If it's stable and the mount is otherwise performing for you, perhaps you're ok.  If it's increasing/recurring (like mine was), you should probably reach out to ES CS and get some help.

The other thing is that, because of that pretty-much-inevitable mesh imperfection, people  developed the technique of balancing their scope 'east-heavy'.  Basically forcing the motors to drive 'uphill' all the time, so that the flanks of the gear teeth always mesh the same way, reducing backlash/play.  You will probably want to look into that as well. Lots of threads on that over on Cloudy Nights.

Hope this helps! 

- Bob


Re: Exos-2 PMC-8 - pier extension & axes stabilty

Steve Siedentop
 

The pier extension for the Orion Atlas EQ-G fits the Meade LXD-75, which the body of the EXOS-2 is based on.  It might be worth checking out to see if it fits the EXOS 2 as well.

-Steve

On Mon, Jun 11, 2018 at 1:01 PM drunkendogg@... [ESPMC-Eight] <ESPMC-Eight@...> wrote:
 

I forgot to let you guys know my name is Jennifer.


Re: Exos-2 PMC-8 - pier extension & axes stabilty

Jennifer Shelly
 

I forgot to let you guys know my name is Jennifer.


Exos-2 PMC-8 - pier extension & axes stabilty

Jennifer Shelly
 

I am going to preface this post with some information about me. The Exos-2 PMC-8 is my first mount. I began my journey with astrophotography a few months ago. I know enough about computers and electronics to be dangerous. Please keep this in mind if you respond.

I own a Exos-2 PMC-8 and I was wondering if it would be possible to get/add a pier extension to give my telescope some additional travel on the RA axis. If so, can someone provide me with some suggestions on how I can accomplish this.

Also, I have noticed that both axes have some wobble when the clutches are locked. The RA axis has the most wobble. Is this normal? If not, what can I do to add stability?


Re: loud noise

Brent Phillips
 

that was the fix thank you 


Re: loud noise

Brent Phillips
 

thank you for the reply I will look at the adjustment


Re: loud noise

W. Christopher Moses
 

I would try it without any gear or counterweight on it. Is it still moving?



On Fri, Jun 8, 2018 at 11:26 AM, brent.phillips79@... [ESPMC-Eight]
wrote:
 

I have noticed a loud noise coming from the motors on the right ascension.  it only happens when the top of the mount is moving to the west.  when it moves to the East it is quiet.  I have checked the balance and everything is balanced good.  Any ideas on what this might be?


Re: loud noise

hubbell_jerry@...
 

Hi Brent,

Is the noise you hear kind of a ratcheting sound?  If so it sounds like the torque required to move the mount is exceeding the torque applied by the motor. The stepper motors will do this if the mount is out of balance (which is not your issue) or if the gear mesh is tight in a certain location where the worm interfaces with the wheel (sometimes called the ring gear). In this case your mount needs to be adjusted. There are instructions on the Losmandy website on how to adjust the worm mesh for the mount here:


I suggest that you disconnect the motor coupler prior to adjusting the worm and then after it looks and feels good when rotating the worm by hand, then reconnect the motor. I know others on the forum can give you additional advice on how to do this. You can also search the G11 forum for additional information.

If you are not sure about doing this, or want to have Explore Scientific adjust your mount, then you should call Customer Service at 866-252-3811 or write service@...

Jerry Hubbell
Director Electrical Engineering
Explore Scientific, LLC.


loud noise

Brent Phillips
 

I have noticed a loud noise coming from the motors on the right ascension.  it only happens when the top of the mount is moving to the west.  when it moves to the East it is quiet.  I have checked the balance and everything is balanced good.  Any ideas on what this might be?


Sky Safari Interface for Explore Scientific PMC-8 Mounts

Steve Siedentop
 

All -


If you have any interest in using SkySafari to control the PMC-8 (without a workaround like Wifi Scope), speak your mind on their support forums...


Even if you don't have any interest, speak your mind.  SkySafari support will go a long way to increase the popularity and visibility of the product, which is good for everyone that uses a PMC-8 product.


https://support.simulationcurriculum.com/hc/en-us/community/posts/360009291573-Sky-Safari-Interface-for-Explore-Scientific-PMC-8-Mounts


-Steve




Re: ASCOMPAD and PMC-8 Connection Problems

hubbell_jerry@...
 

I have created an Explore Scientific Knowledge Base article from this message here:


Jerry Hubbell
Director Electrical Engineering
Explore Scientific, LLC.



---In ESPMC-Eight@..., <hubbell_jerry@...> wrote :

Hi Mark,

There is nothing in the firmware which forces it to select back to WiFi when the PMC-Eight powers up. Unless the ESX! command is sent it will stay at its current value. As has been stated earlier, just powering down the PMC-Eight and powering it back up will not switch the communications port back to WiFi. 

Having said that, you may be seeing that the SSID for the PMC-Eight is still available for connection and you can in fact connect to it as the WiFi module always powers up when booting up the PMC-Eight. The firmware switch selecting the communications channel is stored in the EEPROM memory (permanent) and can only be changed with the ESX! command.

If you cannot make the serial connection work then there is something else going on with your connection. To verify that your serial cable works fine, you can do the following procedure:

1. Connect your serial cable to your computer
2. Determine the com port assigned to your cable.
3. Start the Parallax Serial Terminal Program


4. Select the proper com port and set the BAUD rate to 115200
5. Power up the PMC-Eight
6. The splash screen for the PMC-Eight should show up in the terminal verifying that you have proper communications with the controller.
7. OPTIONAL - You can send a command via the terminal to see the controller respond, %%% (Diagnostics Mode OFF), or ESB! (reboot), 

If you do not see the splash screen, then verify that the controller is actually selected to the WiFi channel by connecting ExploreStars to the PMC-Eight and making sure it works. If that works fine, then do the following:

1. Go through the procedure again to switch from WiFi to Serial.


2. Try and connect to ExploreStars again to make sure you have actually switched to the serial connection.
3. Follow the procedure above to see if you get the splash screen.

Remember, when switching from WiFi to serial using the ESX! command, you should see ESX0! as a response verifying that it is selected to the serial channel. If you do not see a response then it did not switch.

Hope this helps. Let us know how it goes

Jerry Hubbell
Director Electrical Engineering
Explore Scientific, LLC.
 

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