**Imaging error: **Failed to start the exposure [MaxIm error]

[Clifford Kotnik]

I started getting this error about every 10 minutes last night. It seems to occur only with a filter change. I do not see anything in the ACP log indicating an error back from MDL. Attached is an ACP log from one such incident.

The tail end of the MDL for at the time of this failure looked like that pasted below.


I could use some help on this. I don't really see a hint of what is wrong.


Cliff Kotnik

07:30:43*4 Completed 20.000s 3072x2047 exposure, binned 1x1, ROI (0, 0)
07:31:07*4 Started 20.000s 3072x2047 exposure, binned 1x1, ROI (0, 0)
07:31:29*4 Completed 20.000s 3072x2047 exposure, binned 1x1, ROI (0, 0)
07:32:00*4 Started 10.000s 3072x2047 exposure, binned 1x1, ROI (0, 0)
07:32:13*4 Completed 10.000s 3072x2047 exposure, binned 1x1, ROI (0, 0)
07:32:36*4 Started 10.000s 3072x2047 exposure, binned 1x1, ROI (0, 0)
07:32:49*4 Completed 10.000s 3072x2047 exposure, binned 1x1, ROI (0, 0)
07:33:12*4 Started 10.000s 3072x2047 exposure, binned 1x1, ROI (0, 0)
07:33:25*4 Completed 10.000s 3072x2047 exposure, binned 1x1, ROI (0, 0)
07:34:03$5 Guider Tracking Stopped
07:34:06$5 Guider Tracking Stopped

[Clifford Kotnik]

I should point out that I have 14 other cases of this failure for various targets and filter switches from the same night. I can provide them if helpful. In all cases, restarting the plan allowed imaging to continue for awhile.

Cliff

[Clifford Kotnik]

Let me provide further context.

I am very much in the initial stages of getting ACP to run small plans while I adjust things and get smooth operation. I have about 5 nights of imaging and couple more nights where I just focused on calibration. That being said, this is the first night I have seen this failure during imaging. I have had a few failures during flat fielding, but there were additional errors reports like so:
03:03:56 Camera exposing
03:04:01 **Failed to start the exposure
03:04:01 **Script Error (Tracking has been stopped)**
03:04:02 Source: MaxIm.CCDCamera
03:04:02 Message: **Failed to start the exposure
Probably an error in the flat plan

In terms of what may be different this night, I did allow ACP to start MaxIm. I tend to go back and forth on whether I start MaxIm and FocusMax myself or let ACP do it. I guess I still don't trust not seeing the settings in those applications myself.

Let to my own resources, I think I would try disabling the MaxIm camera setting auto-expose after filter change. Reading the PDF manual it sort of sounded like this applies to my STXL filter wheel and it was the default. However, the help topic seems to elaborate that this is for older filter wheels. I do know that filter changes seem to be taking longer than I would have thought. I also know that this ACP error occurs with no pause between the final filter move and the audible error tone from ACP.

If there are other thoughts on what to try or what I can do to collect more info, please advise.

Cliff Kotnik

[Bob Denny]

I would definitely hand-start MaxIm first, then FocusMax (which usually auto-connects to MaxIm), then connect ACP to the camera. With that said, it should not make a difference on the "**Failed to start the exposure" problem.

ACP does not make any audible tones during imaging. MaxIm might be doing it.

Auto-expose after filter change? What? I've never seen this and can't find it in MaxIm 6 now. Do you think that maybe ACP thinks the filter change has completed when in fat it has not? That would be a good hint to pass along to Diffraction. I am going by the data I get back from MaxIm, namely, when it returns back to me after COMPLETING a filter change. I have no way to tell if a filter change is in progress, and in fact I should never see MaxIm with a filter change in progress unless it was done by someone butting in and using MaxIm's controls :-)

[Clifford Kotnik]

Regarding auto-expose after filter change, it is a setting in the camera advanced setup for SBIG Universal. You can see it in this web version of the documentation:
http://www.cyanogen.com/help/maximdl/HIDD_SETUPST7.htm. While the MaxIm PDF manual describes it, the description there is different and does not differentiate between old and new filter wheels.

Given your response, I will conduct my next observing session with this setting disabled and report my findings here.

best regards
Cliff Kotnik

[Bob Denny]

Good! I learned something new. I don't have any cameras here, so I deal with everything on the "top" end of MaxIm.

[Clifford Kotnik]

Bob,
I ran last night with "auto-expose after filter change off" and I still got as many of these failures as before. At one point when I was running a plan with very frequent errors, I turned auto-guiding off. I ran error free long enough to convince myself that further experimenting with auto-guiding is appropriate.

For context, my camera is an SBIG STXL with the FW8G filter wheel. The filter wheel contains the guiding CCD in front of the filters and connects back to the main camera for communications and control.

Here are my ideas on what I will try next. I'd appreciate your thoughts on the usefulness of them and any additional steps to try.

1) I checked the SBIG drivers and firmware for updates. There was no firmware update, but one DLL has had one update that is described "Version 4.93 Build 0 7/29/2016 Start Exposure commands should now complete 100 ms faster than previous version. Adjustments to STF, and STT ...." This will be installed for my next run.

2) I noticed a post in Diffraction Limited (DL) advising a customer to turn off driver debug logging for faster operation. I checked and sure enough the default SBIG installation turned this on and it has been logging on my system. I had not idea it existed. I will run next time with this turned off. If errors persist, I may turn it on and grab it so perhaps DL folks can help us identify what is going on.

3) I would really like to find a way to configure ACP so it does not turn off auto-guiding at the end of each exposure since this works so well when I image with MaxIm alone. In the ACP help is says

• If you specify the same target coordinates in sequential targets, and if you either have an external guide scope or no filters, ACP will leave the guider running across the sequence of co-located targets. Otherwise it re-starts the guider for each target regardless, as the filter may have changed.

How does ACP determine this? Can I specify somewhere that I have the equivalent of an external guide scope?

4) I have MaxIm configured to send auto-guider output to the scope via the ACP ASCOM interface. I will change this to send the output directly to the mount relays via a cable.

Thanks for any assistance you can provide.

best regards,
Cliff

[Bob Denny]

This thread is fracturing into several, I hope I can clear the unrelated issues up right here and now, otherwise I may ask you to start separate ones for the separate issues.

1) I checked the SBIG drivers and firmware for updates. There was no firmware update, but one DLL has had one update that is described "Version 4.93 Build 0 7/29/2016 Start Exposure commands should now complete 100 ms faster than previous version. Adjustments to STF, and STT ...." This will be installed for my next run.

I don't know what this means, but maybe faster is better? I just call a MaxIm function Camera.Expose()

2) I noticed a post in Diffraction Limited (DL) advising a customer to turn off driver debug logging for faster operation. I checked and sure enough the default SBIG installation turned this on and it has been logging on my system. I had not idea it existed. I will run next time with this turned off. If errors persist, I may turn it on and grab it so perhaps DL folks can help us identify what is going on.

Same here. This is below my pay grade... Unless this might affect the issue. I have it on my list to talk with Diffraction about the conditions under which Camera.Expose() can return False.

3) I would really like to find a way to configure ACP so it does not turn off auto-guiding at the end of each exposure since this works so well when I image with MaxIm alone. In the ACP help is says

• If you specify the same target coordinates in sequential targets, and if you either have an external guide scope or no filters, ACP will leave the guider running across the sequence of co-located targets. Otherwise it re-starts the guider for each target regardless, as the filter may have changed.

How does ACP determine this? Can I specify somewhere that I have the equivalent of an external guide scope?

Do you mean successive exposures or successive targets? It does as I described in the help but only for a given target. Whenever a target switches it will stop the guider. If that didn't answer your question please start a separate thread, and begin by posting your question along with the observing plan and the log file showing the guider being stopped and re-started for the same target.

4) I have MaxIm configured to send auto-guider output to the scope via the ACP ASCOM interface. I will change this to send the output directly to the mount relays via a cable.

I'd suggest not doing this as you'll be introducing another variable into the problem. At a minimum you'll need to recalibrate the guider. I'm a bit unclear on why this would be related to camera errors?

[Clifford Kotnik]

Bob,
I'm afraid upgrading the SBIG drivers to the latest and disabling the SBIG driver debug logging did not solve this problem. I have attached the ACP plan, ACP log and MaxIm log for this failure.

I see that MaxIm logs the pointing exposure like so:
04:26:12*4 Started 10.000s 1049x699 exposure, binned 1x1, ROI (1012, 674)
04:26:24*4 Completed 10.000s 1049x699 exposure, binned 1x1, ROI (1012, 674)

There is nothing else there until
04:26:47$5 Guider Tracking Stopped

However, ACP after processing the pointing image records:
04:26:33 Imaging to V0401_Lac-S003-R001-C001-B
04:26:33 Switching from L to B filter for imaging
04:26:33 Focus change of -30 steps required
04:26:34 (taking 10 sec. exposure, B filter, binning = 1)
04:26:34 (using Raw readout mode)
04:26:34 (defocusing -130 steps)
04:26:45 **Imaging error: **Failed to start the exposure
04:26:46 (turning tracking off for safety)

So there is no hint of the B filter exposure making its way to MaxIm.

I look forward to your suggestions on next steps.

best regards,
Cliff

[Bob Denny]

I talked to Diffraction yesterday and we went over the internals of MaxIm to determine under what conditions the function could return False. After eliminating some "impossibilities" we were left with "the camera is already busy and it stayed busy for 5 seconds after you called Expose()". There are 11 seconds including the defocus. Can you please do a run without the defocus operations so we can see the true time from the call to the error? If the defocus takes 6 seconds then this all lines up. But if the error comes back in 1 seconds or something then we're on the wrong track.