problem with communications to Astro-physics 1200

[Michael Richmond]

  I've been trying to set up PhD2 with an Orion StarShoot Autoguider on an Astro-physics 1200 mount.   Let me explain the problem.  I've attached a log file and a couple of screenshots to provide details.

I start running PhD2 and connect to the mount.  I'm using an ASCOM driver for the mount, and it connects just fine.  When it does, a pop-up ASCOM mount-control window appears.   I can use the buttons in this window to operate the mount properly.  For example, when I move the cursor to the "E" icon, and press the mouse button down, the mount slews to the East; when I release the mouse button, the mount stops slewing.  Great!

However, when PhD2 tries to control the mount itself, problems occur.  If I choose the Manual Guiding option, move the cursor to the "East" icon, and press and hold the mouse button briefly, then release it, the telescope starts to move East after a brief pause --- but keeps slewing East, even though I'm not pressing the mouse button any longer.  Moving the "West" icon and pressing the mouse button will cause the telescope to reverse and move West, but again, it keeps moving after I stop pressing the button.

 Likewise, when PhD2 tries to calibrate itself, it begins by sending a brief pulse to move the telescope East (or West).  What happens is that the telescope continues to move East, not making a small motion, but an unending one.  When PhD2 then tries moving in an orthogonal direction, like North, the scope ends up slewing at a 45-degree angle, as it is still moving East as well as North.

 In summary, PhD2's signals aren't being interpreted properly by the mount.  It ought to be using ASCOM for communication, but the stand-along ASCOM control panel works fine.

I've attached a log file in which I connect to the camera and mount, then use PhD2's "Manual Guide" menu to do the following:

   - depress mouse key on "North" button in Manual Guide and release the mouse key.  Mount moves slowly for 5 - 6 seconds as I watch. 

   - I then click the "STOP" button in the ASCOM control window to stop the mount

   - depress mouse key on "South" button in Manual Guide and release the mouse key.  Mount moves slowly for 5 - 6 seconds as I watch

   - I then click the "STOP" button in ASCOM control window to stop mount

   - finally, I quit PhD2

The log file is attached below.

 I've read in other postings in this group that the "synchronous pulse guide" setting in ASCOM driver can cause problems.  It is currently un-checked.  I've attached a pair of screenshots showing the settings of the ASCOM driver and details of my Astro-physics mount control box in case they might reveal some critical information.

If anyone can provide advice or suggestions, I'd be very grateful.

-- MWR

[bw_m...@earthlink.net]

Hi Michael, sorry you’re having trouble.  The AP log file you sent only includes two places I can see where you were trying to issue guide pulses – both 200ms guide pulses, one north and one south.  But I assume those encountered the problem and are representative.  To start, there’s nothing wrong with the communication between PHD2 and the mount driver unless you’re going to say you did many more than 2 Manual Guide commands.  So to cut to the chase, I think you will need to talk to the AP support guys about this.  But let me give you some background based on what I know about this mount.

 

The mount movements you see when using the AP mount-control window don’t use PulseGuide commands – they are using other types of “move” commands and are usually moving the mount at rates higher than the guide speed.  So knowing that these functions work only tells you the PC is communicating with the mount correctly, it doesn’t tell you anything about pulse-guiding.  With AP controllers that are CP3 or later, the mount firmware handles pulse-guide commands with a single transaction – the driver sends it a command like “PulseGuide North 200ms” and the mount performs that operation itself, starting and stopping the motor appropriately.  But I notice you’ve specified that your controller is a CP2 and unless something has changed, the CP2 behaves differently.  With that controller, pulse-guide commands are a two-step operation.  The driver has to first send the mount a command to start the movement, wait the appropriate interval (e.g. 200ms), then send another command to stop the motor. In other words, the driver has to handle the timing, not the mount.  This difference is handled entirely inside the AP ASCOM driver, client applications like PHD2 don’t know anything about it.  So I can think of two possibilities:

 

1. For some reason the AP driver isn’t handling pulse-guides the way the CP2 controller requires, for example by not sending a “stop” command or
2. There is some other hardware-level problem that is causing the operation to not halt correctly

 

Just to emphasize one point, the Manual Guide functions in PHD2 don’t use “click and hold” on the buttons – you press the button once and a single pulse guide command is sent requesting whatever sized move you specified. 

 

I think the AP support guys should be able to get you sorted out pretty easily.  FWIW, upgrading from the CP2 is easy to do and may be worth the investment.

 

Good luck,

Bruce

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[Michael Richmond]

  

   Thanks very much to Bruce for his very quick and informative reply. 

    I contacted Astro-Physics and asked them about this issue.  They said that the CP2 version of the AP 1200 GTO control box could not handle the Guide Move commands used by PhD2; only the more recent CP3 and CP4 versions of the control box can do so.  Right now, the CP4 version is relatively new, so it might be possible to find used CP3 boxes on the second-hand market, if one wanted to take that approach.

     Instead, I will try using the relay communication method, connecting the guide camera to the mount via the phone-jack-type cables.  That ought to work, according to both Astro-Physics and Bruce (if I understood correctly).

      I hope that someone else may find this information useful.  Clear skies, all.

             MWR

[bw_m...@earthlink.net]

Hi Michael.  What you’re talking about is called “ST-4” guiding and it should work fine if you’re careful about how you route the cables.  When you do this, you should also use the “Aux-mount” option in PHD2, specifying the AP ASCOM driver as the aux-mount.  This will provide pointing information to PHD2 so you won’t have to calibrate each time you slew the scope, meridian flips will be adjusted automatically, etc.  You should just use the new-profile-wizard to create a new profile for this approach – guide camera will be the same, “mount” will be “on-camera”, and “aux-mount” will be the AP ASCOM driver.  This is described in more detail in the Basic Use section of the PHD2 manual. 

To view this discussion on the web visit https://groups.google.com/d/msgid/open-phd-guiding/33bcab2a-9c4c-4a48-acd0-5d70d61c82e6n%40googlegroups.com.

[Brian Valente]

>> When you do this, you should also use the “Aux-mount” option in PHD2, specifying the AP ASCOM driver as the aux-mount. 

FYI this is a bit of an "ST-4 Plus" kind of approach where you can get the pointing information via the aux-mount connection so you can calibrate once and use it anywhere in the sky

Brian

To view this discussion on the web visit https://groups.google.com/d/msgid/open-phd-guiding/002c01d8a5e4%24ee2db8d0%24ca892a70%24%40earthlink.net.

--

Brian 

Brian Valente

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