PHD2 Manual Guiding testing, no East-West Movements

[Vanessa Me]

Hello everyone,

I am new to PHD2 and am testing PHD2's Manual Guiding function for troubleshooting purposes. According to the PHD2 manual, Manual Guiding is a good way to test whether or not PHD2 is able to send commands to the mount properly. The weather has not been cooperating since I began testing PHD2, so Manual Guiding is pretty much all I've been able to use, other than image looping. I've tested two connection methods and thus created two different profiles in PHD2 (using the wizard): One profile is for the PC to mount connection and the second profile is for the ST-4 connection from the camera to the mount. My mount is a brand new EQ6-R Pro (the one with the USB type B port on the body). In a nutshell, what I've done is connect to the mount in PHD2, go into Manual Guiding, increase the pulse duration to 5000ms and send 10 pulses in one direction. Then, park the mount to the home position. With the ST-4 connection and profile, PHD2 Manual Guiding works properly in all four directions. With the USB connection and profile however, only the North and South commands seem to work. I can hear the mount move with each pulses and also when parking back to the home position. With East and West commands, even though I see the indication at the bottom of the PHD2 window that a 5000ms command is being sent, I hear nothing and and no movement occurs when parking the mount.

I've looked at my PHD2 debug log and for the life of me cannot see any difference between  a North command log and a West command log.

I initially used a short USB type B to USB cable to connect the mount to my PC, but have since been encouraged to try a serial to USB cable from Pegasus Astro to see if it fixed the issue. This cable plugs into the hand controller port on the body and the other end plugs into the PC. Other than the baud rate configuration, there is no difference and the results are the same.

I would prefer to use the USB connection rather than the ST-4 connection for guiding.

As mentioned, This is a brand new mount so I'm trying to determine at this point if there is something wrong with it.

 

Any help would be appreciated. Attached is a Debug log file with two manual guiding commands sent, one North and one West. The camera is not connected.

Thank you.

[Bruce Waddington]

Hi Vanessa.  To use the ASCOM mount interface, you need to set up EQASCOM according to these parameters:

https://github.com/OpenPHDGuiding/phd2/wiki/EQASCOM-Settings

It's also important that you aren't pointing the scope near the celestial pole.  In any scenario where you're trying to test guiding, you should be pointing somewhere close to Dec = 0 - or where Dec = 0 would be if you were under a nighttime sky.  If doing these things doesn't resolve your concerns, let us know and I'll give you a link to a mount exerciser test program you can use in the daytime.

Regards,

Bruce

[Vanessa Me]

Hi Bruce,

Thank you for replying. I confirm to you that EQASCOM is setup the same as the link you provided. As for the declination of the mount during testing, I have it set to 0 (pointing toward the horizon). Does my PHD2 Debug log look normal to you? I also read in another discussion on here that the ASCOM logs could also potentially give clues, but when I look at them, all I see are the Connect.Form logs (assuming I'm looking in the right directory). There is no information in there that pertains to movements. I also look forward to that exerciser test program you mentioned.

Thank you.

[KTAZ]

" If doing these things doesn't resolve your concerns, let us know and I'll give you a link to a mount exerciser test program you can use in the daytime."

I would absolutely LOVE to have this. Can you send me a link?

Thanks

Ken

[Bryan]

Vanessa

Something is awry in the setup, if Dec = 0 is pointing at the horizon. (Unless you are close to one of the poles!)

For calibration, in addition to pointing at Dec = zero (plus/minus 20 degrees), you also want RA axis pointed at the meridian (plus/minus one hour or about 15 degrees).  This point will not be at the horizon, but pointed overhead and at an altitude equal to 90 degrees minus your latitude.

This is because the apparent motion of the sky is greatest at this point; hence, the calibration will be most precise.  Think about is you pointed at Polaris.  You could turn the mount off and guiding would look great.

There are several ways to point your OTA at this intersection.  One is using PHD2.  Since you are planning a calibration, then in PHD2, click Tools -> Drift Align .  A dialog box will open.  Using the defaults (Meridian Offset = 0 and Dec =0), Click Slew.  Close Drift Align and proceed with calibration.

Bryan

[Vanessa Me]

Hi Bryan,

In EQMOD interface, Dec is +90:00:00, but physically I have the mount declination at 0, at the home position (scope straight ahead with the counterweights pointing toward the ground). I'm not doing calibration at the moment. I'm just trying to get the mount to respond to PHD2 Manual Guiding commands in all directions.

[Bruce Waddington]

Hi Vanessa.  It sounds like you are a little confused about the celestial coordinate system.  If the mount says you were pointing at Dec=90, you were pointing close to the celestial pole and that's why the RA guide pulses weren't creating any obvious movement.  Things like "home position" and "scope straight ahead" aren't generally useful descriptions because those things vary by the type of mount.  Some mounts have no concept of a pointing position, others have many different ones, etc.  In addition to actual RA and Dec coordinates that we talk about, there are several celestial position terms we use a lot in guiding and here's one way to figure out where they are in the sky assuming you're in the northern hemisphere:

1.  Figure out roughly what the latitude is for your location.

2.  Face west and point your right arm north.  Elevate your arm so that the angle between your fingers and the north horizon is equal to your latitude. You will be pointing close to Polaris at this point, close to the north celestial pole, and the declination will be 90.

3.  Point your left arm directly overhead - that is the zenith point.

4.  Sweep your left arm from Polaris, through the zenith point, and down to the south horizon.  You have just traced the imaginary arc called the celestial meridian.

5.  Now point your left arm at the south horizon and move it back to the north along that same arc - along the celestial meridian - until your fingers are (90 - latitude) degrees above the south horizon.  At this point your left and right arms will form an angle of 90 degrees, they will be perpendicular.  Your left arm is now pointing at the celestial equator and that is the ideal position for doing calibrations and testing your mount's tracking and guiding capabilities.  At this position, your Dec will be zero.

Hope this helps,

Bruce

[Vanessa Me]

Hi Bruce,

Sorry if my description of the position of the mount wasn't clear. I'm not yet using the appropriate terms. My latitude is 45°31'00" N. Still, does the position of the mount really matter in this case? I am not doing calibration or tracking or guiding at this stage. I'm using PHD2 Manual Guiding purely to check that the mount is responding to pulse guiding commands from PHD2, as described on p.37 of the PHD2 manual:

"...you will probably want to be sure that PHD2's commands are actually getting to the mount. Or you may want to nudge the mount...In the 'Tools' menu, click on 'Manual Guide' and a dialog will appear to let you move the mount at guide speed in any direction...Each time you press the button, a pulse of the duration specified in the 'Guide Pulse Duration' field will be sent. The default value is the 'calibration step-size' set in the Advanced Settings dialog. If you are debugging mount/calibration problems in the daytime, listen to (rather than watch) your mount to determine if it is getting the commands from PHD2. The idea here is just to figure out if the mount is responding to PHD2's signals. You won't be able to see the mount move (it's moving at guide speed) but you may be able to hear the motors."

As I initially stated, when using the ST-4 connection from the guide camera to the mount, in an "On camera" configuration in PHD2, Manual Guiding commands work fine in all four directions, regardless of the mount's position. With the serial USB connection, only North and South Manual Guiding commands work. Both DEC and RA pulse guide rates in EQMOD are set to 0.90x. I hear the motors when issuing a command and see the mount move when parking back to the home position. I also tried this with the mount polar aligned. Same results.

[Bruce Waddington]

Yes, I understand what you're doing.  You're asserting that the RA guide commands "don't work", but based on what?  Not hearing the motors?  I don't know what state the mount is in or, more importantly, what state EQMOD thinks the mount is in.  I think you're putting the system into a weird state and I don't know how the mount driver will respond.  Pulse-guiding while pointing at the north celestial pole is a weird state.  Why are you so resistant to slewing the scope away from that area as we've suggested?  Or for that matter, couldn't you just wait for a usable nighttime sky and proceed normally?  There's nothing in the log to suggest a problem with RA pulse-guiding, and EQMOD is a tried and true way to connect to the mount. 

If you really can't wait to test the mount, you can use this Mount Exerciser tool - an instruction document is included in the folder.  But even with this tool, you must unpark the mount and get it pointing away from the north celestial pole.

Mount Exerciser Tool

Let me know if you have any problems with it or the instructions don't make sense to you.

Good luck,

Bruce

[Vanessa Me]

Hi Bruce,

" I think you're putting the system into a weird state and I don't know how the mount driver will respond.  Pulse-guiding while pointing at the north celestial pole is a weird state.  Why are you so resistant to slewing the scope away from that area as we've suggested?"

I tried both. I first tried pointing at the North celestial pole because, well when you're a noob like me, setting up the mount step by step ultimately results in the mount pointing towards Polaris (artificially, since I haven't had a single clear night since I got the mount). Following your suggestion however, I slewed at the celestial equator and tested PHD2 manual guiding tool, but got the same results as before (North and South commands work, East and West don't).

The mount is brand new (Sky-Watcher EQ6-R Pro), got it at the end of March and have not had a single clear or partially clear night to put it to real world test, so we set it up in the living room. This is our first ever mount and there's a lot to take in and to try to make sense of, but I took it in stride and solved issues one at a time. Everything appeared fine right up until I watched some videos and read about how I should not be using ST-4 for guiding and instead should be pulse guiding using the mount to PC USB connection.

My logic was simply that if I hear the motors and see the mount move when using PHD2 Manual Guiding with ST-4, I should also expect the same results with pulse guiding through the USB connection. Perhaps that is a wrong assumption but I'm hard pressed to find any information clearly telling me otherwise. The thing is, I have years ahead of me to learn everything there is to learn about astrophotography but I only have a short window to determine whether or not the mount is defective. The shop I bought the mount from suggested that perhaps the issue I'm having could be firmware related and could potentially be bypassed by using a special serial-USB cable from Pegasus Astro plugged into the hand control port on the mount and into the PC. I tried this also but the results are the same.

There is a lot I have yet to grasp about all of this. Truth be told I don't yet understand why pulse guiding is better than ST-4, other than one less cable to manage and that the guiding software knows when the scope is East or West (or something along those lines). I think that I understand that EQMOD assumes that the mount is polar aligned when you launch it and that is why it shows a declination of 90, but I could be wrong there too. I also don't understand if tracking needs to be on or off in EQMOD when using PHD2 Manual Guiding. With GS Server (which I also tried) you cannot use PHD2 Manual Guiding unless tracking is on. If doing so, PHD2 produces a clear error message about pulse guiding failure.

On the bright side, at least now I know that my PHD2 debug log seems normal. At the end of the day, if PHD2 Manual Guiding tool is not a good way to quickly tell if the mount is properly responding to pulse commands, I'll try something else.

Thank you for exerciser tool. I'll give that a try.

[Vanessa Me]

UPDATE

Hi again Bruce,

I uninstalled/re-installed EQMOD, re-did the setup in EQMOD and PHD2 (new USB connection profile). I enabled tracking in EQMOD and PHD2 manual guiding commands appear to work in all 4 directions now. I'm using the Pegasus Astro serial-USB cable, which uses the default baud rate of 9600 instead of 115200. Not sure what solved this. I'll do further testing to narrow it down.

Thank you.

[Bruce Waddington]

Ok, I'm glad you made some headway.  For pulse-guiding to work, tracking must be on in the mount.  Guiding in RA is accomplished by making tiny, brief adjustments in the speed of the RA drive system but the mount must be tracking at the sidereal rate on its own.  The numerous advantages of using ASCOM pulse-guiding are spelled out in the PHD2 manual:

https://openphdguiding.org/man/Basic_use.htm#ASCOM_Benefits

If you haven't studied this 'Basic Use' part of the manual, you probably should, it will save you a lot of time and frustration.

Regards,

Bruce