Fighting a losing battle with PHD2

[Stub Mandrel]

I use a ZWO ASI120MC for guiding with PHD2.

I never have problems finding stars, but often have issues with poor connectivity with the camera. This seems to have got worse of late.

What happens is that the time between frames gets longer, and longer and longer...

Reconnecting the camera, in software or by unplugging it makes no difference. Restarting PHD2 makes no difference. Restarting the computer sometimes works.

The only thing that works reliably is:

• Close PHD2
• Open the camera in Sharpcap (where it invariably works)
• Close Sharpcap.
• Reopen PHD2 and reconnect the camera which will now work reliable for 'a period of time' which could be ten minutes or a few hours...

 

The problem is somewhat intermittent and I have a suspicion it might be EQMOD related, not just PHD2. I am sure it isn't a camera/driver issue as it always works fine in Sharpcap. Note that 8 bit/16 bit mode doesn't seem to affect this.

 

[michael8554]

Sounds like a USB bandwidth problem.

Experiment during the day with a short USB cable, and lightly capped, so you get a grey frame with PHD2 slider adjusted, at your usual exposure.

Try it in all your USB's with nothing else connected.

If that works add more kit and longer cables until it starts to be "throttled". 

Michael

[kens]

Could you post a guide log and maybe even the debug log? 

For instance, it could be that there is a long wait time for the mount to respond causing delays on each expsoure

[Stub Mandrel]

On 22/09/2020 at 00:20, michael8554 said:

Sounds like a USB bandwidth problem.

Experiment during the day with a short USB cable, and lightly capped, so you get a grey frame with PHD2 slider adjusted, at your usual exposure.

Try it in all your USB's with nothing else connected.

If that works add more kit and longer cables until it starts to be "throttled". 

Michael

I'm using a 1.5m quality cable 😞

I've always had best results in Sharpcap allowing it to auto-set the USB speed.

But PHD2 doesn't have such a feature.

Edited September 23, 2020 by Stub Mandrel

[Stub Mandrel]

On 22/09/2020 at 00:48, kens said:

Could you post a guide log and maybe even the debug log? 

For instance, it could be that there is a long wait time for the mount to respond causing delays on each expsoure

Could be, I will try and find it.

But at the time it had been guiding as well as 0.52", ticking away every 2 seconds then .... it just fell over, sometimes a minute or more before getting a frame, and some split frames.

 

[Colinhunter]

I use the same camera. if I use the asi driver I Have the same problem. If I use the ascom2 drivers it works ok. Might be worth a try

Edited September 23, 2020 by Colinhunter

[Stub Mandrel]

7 hours ago, Colinhunter said:

I use the same camera. if I use the asi driver I Have the same problem. If I use the ascom2 drivers it works ok. Might be worth a try

Thanks Colin.

[tooth_dr]

I have a 120MM that I’ve went back to for guiding, and it does the same as yours, PHD 2 problems with longer exposure times, then it will go back to normal, and also split frames. I just assumed it was the camera, so will be interested to see if you find a solution.