View Full Version here: : PHD2 woes with ZWO and EQMOD...advice please

02-10-2017, 08:47 PM
http://i39.photobucket.com/albums/e185/Tokyo1989/My%20Astro%20setup%20small_zps0eiwz t3b.jpg

Hi all,
Hopefully someone may be able to help?
I'm trying...again...to get everything to happily work together but PHD2 won't cooperate.
The main hardware I'm using:
1. NEQ6 with EQMOD and William Optic 132
2. 50mm guide scope with ZWO290MC
The software is:
1. ASCOM and EQMOD. Pulse guiding is checked
2. Cart du Ceil
3. PHD2
I have the ZWO connected to the computer and the the computer to the mount with the Shoestring DB9 plug.

I can see the star image in PHD2 but cannot get enough movement west after 60 or so iterations. In the PHD2 manual it says to take manual control to check the mount is talking to PHD2 but that doesn't work either. I've checked the calibration data and increases the duration of the pulse but no luck.

Am I missing something here? Does anyone haven advice please as I'm feeling frustrated after several days on just this issue.

PS why do I see the image in preview but only as a link in the actual thread?

02-10-2017, 09:08 PM
Can you make the mount move with eqmod?

02-10-2017, 09:22 PM
Yes Peter all is well with EQMOD. I can drive the mount with the game pad or from the EQMOD control panel.

02-10-2017, 09:23 PM
What do you have selected as the telescope in PHD2

02-10-2017, 09:33 PM
For the telescope in the Advanced Setup and Guiding tab: Focal length 162mm as its an Orion guide scope which give calibration steps of 1050 which in Manual mode I extended to 5000ms.

In the connect to equipment tab on the bottom left I've tried two different ways
Camera: ZWO Camera
Mount: On camera

Camera: ZWO
Mount: On camera
Aux Mount: None


02-10-2017, 09:38 PM
To use on camera you need the st4 cable connected from the zwo to the guide port on the mount. You are better off using ascom pulse guiding. For that you enable pulse guiding in eqmod setup and select eqmod ascom heq5/6 as the mount in phd2

02-10-2017, 09:43 PM
Thanks Peter, I will try that :)

02-10-2017, 09:46 PM
You can still use on camera with the ST4 cable connected to the mount. Just select the ZWO camera and on camera connection on start up. I do it that way with no issues at all. Make sure your guide star SNR is above about 10 and set the exposure to 2 sec to start with.

02-10-2017, 09:58 PM
Thanks Glen. I did use the auto guide port on the EQ6 and on camera until a few months ago when it all stopped working for some reason hence the revisit to EQMOD.

03-10-2017, 06:41 AM
The advantage of using eqmod pulse guiding is that all the signals to the mount motors come through a single interface so you avoid eqmod saying drive forward for siderial tracking while the st4 connection is trying to slow the mount down for guiding.

Here's some reference material from the author of eqmod....



03-10-2017, 07:03 AM
No doubt, i was not suggesting multiple interfaces, my point being the use of EQMOD is not required for good guiding, you don't need it. There is no requirement in imaging, or guiding, to control the mount from a laptop. Mounts work very well using the range of alternative control interfaces available, including standard hand controllers, wifi interfaced devices running Sky Safari, etc. Sure you need a app platform for PHD2, or Metaguide, and a camera app of some sort, but mounts respond to guide commands just fine without EQMOD.

03-10-2017, 08:17 AM
Pretty sure Geoff is already using eqmod and he also needs a computer to drive his zwo camera. In this case the st4 connection is not required.

03-10-2017, 03:16 PM
I have not got the solution to your problem,..........not a good reply is it,............. I have the identical fault, PHD2, Neq6, Zwo camera etc, running Eqmod in pulse, etc, I have tried 3 different computers, replaced all the leads, tried to guide in ST4, which worked once, gave me a flaky calibration then stopped working , changed every setting in Eqmod and PHD2, uninstalled the software and reinstalled, I connected an oscilloscope to the mount to watch the signal, this proved to be inconclusive or perhaps I just dont know anough above pulse widith modulation signals .......... I'm totally out of ideas after 5 weeks of effort.

I've spoken to service at Tasco who was very helpful, he sent me a replacement mother board for the mount, which I installed, the problem remains.
I can use manual mode in PHD2 and watch the "pulse guide monitor" window and see the pulses being sent as I push direction buttons in PHD2, (Dec works ok),
I checked the continuity of the windings on the RA stepper motor, which appear ok,

I have come against brick wall.

I've spoken to the tech at Tasco, he is currently looking into a solution at the moment.

None of this is fixing ur problem but at least ur not alone on this, if I come up with a solution, I will let you know,..... the solution may be returning the mount to the dealer, and buying another brand mount.

You can contact me offline if you would like to discuss this further

regards Russ

03-10-2017, 05:22 PM
In eqmod when you hold down the ra and dec buttons does the mount move?

04-10-2017, 04:39 AM
G'day Peter, yes the mount moves in both axis

04-10-2017, 07:29 AM
I think phd2 also has manual mount jogging buttons. Does it move when you try these?

04-10-2017, 07:39 AM
Only Dec. axis moves, Ra is the problem.

04-10-2017, 09:50 AM
Have you got the same guide rates set in eqmod for both ra and dec?

04-10-2017, 10:09 AM
Tried different rates without any reponse from ra

------Geoff, hope I'm not hijacking your thread-------

04-10-2017, 12:05 PM
Are you using pulse guiding via eqmod or st4 connection?

04-10-2017, 05:36 PM
I've tried both I managed to get PHD2 to calibrate in St4 , the cal was flaky to say the least, but it guided for 10 minutes or so and then stopped, I hav'nt been able to get it to calibrate since.

04-10-2017, 05:57 PM
Might be time to start a new thread with a description of how you have things connected and the connection info from phd2.

07-10-2017, 11:23 AM
Also it might pay dividends to ditch PHD2. I used it for a while. It has some nice features but I found it was not as robust and reliable as CCDsoft.

Pulse guiding may also be an issue. I thought that was an AstroPhysics Ray Gralak invention. I did not know it was available outside of that. So is the software capable of utilising it? It may be easier to use the more usual guiding cable and ST4 style relays. I have used both and I don't see a lot of difference in guiding accuracy. Perhaps there is some gain but its not obvious.

In general in astrophotography, because everything really tends to be a but fussy and precious it makes sense to use the thing that works every time rather than a newest and latest that potentially is buggy. That's where these forums are good as you can find out what's reliable and what's not.

If you had PHD2 working in the past perhaps revert back to what worked in the past or if it was some other software than use that.

The SkyX now seems mature and stable and has been for a while and runs everything, mount, camera, focuser, autoguider.


07-10-2017, 11:40 AM
I had major issues with phd2 dropping out and doing all sorts or weird things. Spent ages trying to get a basic guide happening......now it's working perfectly.

What did I do you ask.....in eqmod I unchecked the "mount limit" box......has worked flawlessly since.

07-10-2017, 09:10 PM
Darn, I managed a little more progress last night but still no luck.

So, I took manual control in PHD2 and by increasing the duration to around 3000 I was able to drive the mount in each direction. As soon as I clicked on a star the PHD icon would turn green but then when I would try to select it to start guiding it change from green back to grey and then give the message "Star lost"...aw man this is frustrating.

Any other ideas please?


08-10-2017, 07:13 AM
Your issues sound like they are most likely mechanical or electrical.
You need to approach this methodically and elimnate as many variablea as possible while testing.
As a first step my approach would be to conduct a star cross test using first just EQMOD or hand controller and then using PHD2

08-10-2017, 07:17 AM
Greg it might be worth trying another computer to mount interface to eliminate the shoestring this outfit in Melb sells a TTL/usb device that does the same job as the Shoestring, it is a quarter of the price of the shoestring,


You will need to buy a db9 plug from Jaycar and replace the header with the db9, details are on the page, or here-


08-10-2017, 07:53 AM
I doubt the problem is with the cable if he can successfully drive the mount in both directions with eqmod.

13-10-2017, 07:21 AM
Hi all,

Thanks for your help and patience. I managed to get a few hours last night and got it to track but not as well as I could with PHD. I used to be able to get 0.17" RMS but as you can see it wasn't so good last night. The sad thing is I'm not sure why it worked when I did everything the same as before.

I did have trouble though trying to force it to calibrate away from zenith and take new dark frames but I suspect that's just user impatience or error.

The star in the pic is Alpha Cen after a slew to check pointing, which was pretty good.

Anyway onwards and upwards hopefully.
Cheers and thanks again

13-10-2017, 08:04 AM
I note your guide exposure is only 0.5s.
It would be better to guide on a nearby fainter star and get the exposure up to 1.5 or 2 sec. This would better average out the seeing.

13-10-2017, 09:40 AM
Hi Geoff,
I have been having pretty much had the same issues as you. My mount is an AZ-EQ6 with EQMOD and guide camera is an ASI120 MM-S.

I had to do a few things to get everything stable:
1. Make sure you have the latest drivers from ZWO, they recently released a new version.

2. I find the ZWO drivers are quite unstable, both native and ASCOM, so I make sure I only run everything after a clean boot and only run the software I absolutely need to for imaging.

3. I confirm I can connect to my guide camera and that it is working as expected each session. I usually do this in PHD2 once I have connected to the camera and then hit the loop button, I also fine tune my exposure settings at this point.

4. When start EQMOD I make sure off PPEC is off.

5. In PHD3 I always make sure the exposure is 2 seconds or above.

Hope this is helpful.

Forgot to mention, I am using pulse guiding.

14-10-2017, 06:02 AM
Thanks Ken and Simon, I’ll try longer exposures and reboot too.

14-10-2017, 10:22 AM
If you're using pulse guiding the mount shouldn't be set to "on camera" in PHD2, with that setting it will be trying to guide though the st4 port on the camera. You should be using the "EQMOD ASCOM HEQ5/6" option in mount when setting up.

Edit, Didn't see that someone else already said this :rofl: