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PHD2 - RA Calibration failed : star did not move enough

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#1 S.Capici

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Posted 09 March 2021 - 04:11 AM

Hi all

I am trying to set up my auto guide (an ZWO ASI 120MM camera with a 80/400 guiding scope on HEQ5 synscan pro mount).

Cable connections are as follows :

camera connected to PC with USB cable 

mount connected to PC  with USB cable from synscan hand controller to PC

camera to mount with ST4 cable

I created a new user on PHD2 selecting the camera (ZWO ASI Camera) and the mount (EQMOD HEQ5/6 (ASCOM))

I connect both  and I see the images of the camera on the screen and I can move the mount through the NSWE buttons on EQMOD form.

 

After choosing a star to follow,  calibration starts but after some tens of seconds I get the error message
 

RA Calibration failed : star did not move enough

 

What went wrong ?
Did I make a mistake on the PHD2 settings or on cable connections ?

Anyone can help ?

 

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#2 happylimpet

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Posted 09 March 2021 - 04:22 AM

Are you really at +90 dec? there wont be any movement in RA when you calibrate there - you're at the pole! You want to be near the equator.

 

Also, you dont need the ST4 cable if youre using EQMOD and can move the mount via the buttons on the EQMOD GUI.


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#3 barbarosa

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Posted 09 March 2021 - 04:30 AM

You may have already checked the Help item from the PHD2 top menu, but if not here is a section of Help Trouble Shooting Section that covers the problem-- (emphasis added)

 

Calibration and Mount Control Problems
If you are just starting to use PHD2 or are connecting to new equipment for the first time, you may have trouble getting calibration done.  This problem usually takes one of two forms, each requiring different responses:
1.
The star moves during calibration but it moves "too far" or "too little."  If you've used the new-profile wizard and have provided correct values for focal length, camera pixel-size, and mount guide speed setting, the "step-size" used in calibration should already be correct.  But if you've configured your profile by hand or have changed guide speed settings in the mount, you may need to adjust the 'calibration step-size' parameter in the 'Guiding' tab of Advanced Settings. The help content there describes how this parameter is used, and you should be able to resolve the problem quickly.  But if you've used the new profile wizard and are seeing problems with "too far" or "too little" guide star movement, the problem probably lies elsewhere.
2.
The star doesn't move enough during RA calibration, declination ('Dec') backlash clearing, or Dec calibration.  These problems are announced by alert messages at the top of the display window.  With longer focal lengths, small movements may even be the result of seeing deflections, and the mount isn't really moving at all.  Dealing with this sort of problem is described next.

In nearly all cases, the "no movement" problem is caused by failures in the mount or in the cabling and connections.  The best tool for trouble-shooting this is the 'Manual Guide' option under the 'Tools' menu, as described in the Tools section of this help document.  Simply use the directional controls in the 'Manual Guide' window to send commands directly to the mount while watching a star in the image display window.  Use fairly large guide pulse amounts - at least several seconds - so you can clearly see if the mount is moving.  Try to move the mount in all four directions and verify the target star is moving by roughly equal amounts.  If the mount does not respond, you know you have either hardware or connectivity problems to resolve - nothing to do with PHD2.  If you're using a Shoestring device to connect to the mount, watch its indicator lights to see if the commands are reaching it.  Similarly, your ST-4 compatible guide camera may have indicator lights to show when guide commands are being received.  If you're using an ASCOM connection to the mount, be sure the COM port assignments are correct.  You can also use some of the ASCOM-supplied tools like POTH to be sure the ASCOM driver is communicating correctly with the mount.  It is best to use the latest version of the ASCOM driver for your mount because older versions of these drivers might have bugs associated with pulse-guiding.



#4 S.Capici

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Posted 09 March 2021 - 04:36 AM

Are you really at +90 dec? there wont be any movement in RA when you calibrate there - you're at the pole! You want to be near the equator.

 

Also, you dont need the ST4 cable if youre using EQMOD and can move the mount via the buttons on the EQMOD GUI.

No I was not at +90dec when I got the error . I was pointing to M101.

The picture with +90dec refers to my today trials at home I attached it just to show the settings.

 

Are you saying that I have to not use the ST4 cable and PHD2 will be able to apply corrections even if that cable is not used ? 



#5 S.Capici

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Posted 09 March 2021 - 04:38 AM

You may have already checked the Help item from the PHD2 top menu, but if not here is a section of Help Trouble Shooting Section that covers the problem-- (emphasis added)

 

Calibration and Mount Control Problems
If you are just starting to use PHD2 or are connecting to new equipment for the first time, you may have trouble getting calibration done.  This problem usually takes one of two forms, each requiring different responses:
1.
The star moves during calibration but it moves "too far" or "too little."  If you've used the new-profile wizard and have provided correct values for focal length, camera pixel-size, and mount guide speed setting, the "step-size" used in calibration should already be correct.  But if you've configured your profile by hand or have changed guide speed settings in the mount, you may need to adjust the 'calibration step-size' parameter in the 'Guiding' tab of Advanced Settings. The help content there describes how this parameter is used, and you should be able to resolve the problem quickly.  But if you've used the new profile wizard and are seeing problems with "too far" or "too little" guide star movement, the problem probably lies elsewhere.
2.
The star doesn't move enough during RA calibration, declination ('Dec') backlash clearing, or Dec calibration.  These problems are announced by alert messages at the top of the display window.  With longer focal lengths, small movements may even be the result of seeing deflections, and the mount isn't really moving at all.  Dealing with this sort of problem is described next.

In nearly all cases, the "no movement" problem is caused by failures in the mount or in the cabling and connections.  The best tool for trouble-shooting this is the 'Manual Guide' option under the 'Tools' menu, as described in the Tools section of this help document.  Simply use the directional controls in the 'Manual Guide' window to send commands directly to the mount while watching a star in the image display window.  Use fairly large guide pulse amounts - at least several seconds - so you can clearly see if the mount is moving.  Try to move the mount in all four directions and verify the target star is moving by roughly equal amounts.  If the mount does not respond, you know you have either hardware or connectivity problems to resolve - nothing to do with PHD2.  If you're using a Shoestring device to connect to the mount, watch its indicator lights to see if the commands are reaching it.  Similarly, your ST-4 compatible guide camera may have indicator lights to show when guide commands are being received.  If you're using an ASCOM connection to the mount, be sure the COM port assignments are correct.  You can also use some of the ASCOM-supplied tools like POTH to be sure the ASCOM driver is communicating correctly with the mount.  It is best to use the latest version of the ASCOM driver for your mount because older versions of these drivers might have bugs associated with pulse-guiding.

I saw it, I checked all cable connections and they look fine. I guess/hope there is something wrong on what I am doing



#6 KenS

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Posted 09 March 2021 - 04:44 AM

Check your EQMOD settings:

https://github.com/O...QASCOM-Settings

 

EQMOD default to a guide rate of 0.1x sidereal which is way too low. 0.5x to 0.9x is recommended.

If that does not work please attach your logs either here or at the PHD2 support forum. Details at https://openphdguidi...g/getting-help/


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#7 S.Capici

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Posted 09 March 2021 - 04:49 AM

Check your EQMOD settings:

https://github.com/O...QASCOM-Settings

 

EQMOD default to a guide rate of 0.1x sidereal which is way too low. 0.5x to 0.9x is recommended.

If that does not work please attach your logs either here or at the PHD2 support forum. Details at https://openphdguidi...g/getting-help/

thanks it was 0.1x . I now changed it to 0.9x, I will check this night if it works.
What about ST4 cable, I was suggested in above message to not use it as I am using EQMOD ... Sorry to ask but new here and a little bit confused



#8 KenS

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Posted 09 March 2021 - 05:52 AM

thanks it was 0.1x . I now changed it to 0.9x, I will check this night if it works.
What about ST4 cable, I was suggested in above message to not use it as I am using EQMOD ... Sorry to ask but new here and a little bit confused

That advice is correct. You do not need ST4 if you are using EQMOD. However, an EQDIR cable would be preferable to connecting via the handset

When you use PHD2 next, recalculate the calibration step size to take into account the changed guide rate. Click the Advanced... button next to Calibration step size

https://openphdguidi...htm#Guiding_Tab


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#9 Tapio

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Posted 09 March 2021 - 05:56 AM

That advice is correct. You do not need ST4 if you are using EQMOD. However, an EQDIR cable would be preferable to connecting via the handset

Not sure about this.

You can connect cable directly to mount and then no need for HC.



#10 KenS

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Posted 09 March 2021 - 06:09 AM

Not sure about this.

You can connect cable directly to mount and then no need for HC.

OP said he has a USB serial cable connected to the handset which would need to be in PC-direct mode. To connect directly to the mount you need an EQDIR cable which is a different kind of cable.



#11 David Boulanger

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Posted 09 March 2021 - 06:58 AM

My Synscan hand controller does not need to be in PC Direct Mode for it to receive guiding pulses from PHD2 via USB




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