Jim Smith avatar
Last night I was hoping for some trouble free autoguiding as I thought I had my problems ironed out...but no!

I was running PHD2, EQMOD and SharpCap Pro on my Windows 10 laptop. A Lynx Astro FTDI EQDIR USB Adapter for Sky-Watcher Mounts connected my laptop to the mount.

In my previous session I had discovered that setting the Total Steps to 5184000 and the Worm Steps to 38400 and the communications baud rate to 115200bps on the EQASCOM setup screen gave me good autoguiding. The baud rate change was particularly important as before that PHD2 couldn't even send manual guiding pulses to the mount successfully. With these settings I managed to get sub 1 arcsecond guiding for several minutes before I had to pack things away.

But last night I couldn't connect to my mount at all. Neither EQMOD or PHD2 could connect. I checked the cables and the COM port but all looked OK. In the end I changed the EQASCOM baud rate back to the default 9600 and now I could connect again!

Unfortunately my autoguiding run showed 4.63 arcseconds and the graph showed that the guiding pulses were not sufficient to correct for my mount's periodic error. I have attached the PHD2 log file if anyone is interested in taking a look.

I will take a look at PHD2 PEC training soon but first I was wondering if anyone knows which baud rate I should be using with my set-up. Why does the suggested rate (http://eq-mod.sourceforge.net/prerequisites.html) only sometimes work?

Thanks, Jim

PHD2_GuideLog_2022-07-03_235800.txt
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Jim Smith avatar
Update…

I have discovered that I can connect my laptop to the mount with an ordinary USB type A to type B cable. Apparently I don't need to use the FTDI EQDIR cable at all. I tried it this afternoon and it connected at 115200 baud just fine. It should be clear tonight so I can run another autoguiding test .
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Andy Wray avatar
I've always used the defult 9600 baud with my FTDI cable FWIW.  Guides sub-1 arc sec.  You don't need a lot of bandwidth to send a guiding correction every 1 or 2 secs.
Jim Smith avatar
Andy Wray:
I've always used the defult 9600 baud with my FTDI cable FWIW.  Guides sub-1 arc sec.  You don't need a lot of bandwidth to send a guiding correction every 1 or 2 secs.

Andy, is that with an AZ-EQ5-GT mount?
Jim
Andy Wray avatar
Jim Smith:
Andy Wray:
I've always used the defult 9600 baud with my FTDI cable FWIW.  Guides sub-1 arc sec.  You don't need a lot of bandwidth to send a guiding correction every 1 or 2 secs.

Andy, is that with an AZ-EQ5-GT mount?
Jim

Sorry .. that's with a Skywatcher HEQ5 Pro mount.  That said, I still believe that using an FTDI cable you should probably go for the lower baud rate.
Jim Smith avatar
I ran another autoguiding test with the ordinary USB cable connecting to the mount. I checked which COM port it was using in Device Manager and entered that COM port in EQASCOM. SharpCap and PHD2 both connected straight away. A small success!

I checked that EQMOD allowed me to slew the mount and go to named stars. That worked too.

I checked that PHD2 was could loop and find stars. Yes, all fine.

I slewed to a bright star, Deneb I think, and tried autoguiding with my saved calibration. The results were very poor. The graph showed guiding pulses, but PHD2 couldn't correct enough for RA deviations. I ran the guiding assistant and noticed that tracking seemed no worse when autoguiding was turned off!

I thought I would do a new calibration. I slewed to within about 5 degrees of the meridian and celestial equator. It failed because PHD2 couldn't move the mount sufficiently to complete the process. I'm not sure it was moving the mount at all.

I am getting the impression that on my set-up PHD2's guiding pulses might work for a while, but after, say, 10 or 20 minutes the mount simply doesn't respond to them. It seems almost everybody uses PHD2 so I don't think that's the problem. I have tried two different connections to the mount so it would be very bad luck if they were both faulty. I think it might be the mount. My laptop has only one USB port so I have to use a hub. (It is a USB 3.0 one.) Perhaps using a hub is a problem?

I am going to try using an ST-4 cable next time, and I'm going to check if the mount's firmware is upgradeable.

Any other ideas?
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Andy Wray avatar
In EQASCOM, what are your RA and DEC PulseGuide rates set to?  Mine are at 0.8x.  If they are too low I could imagine you having this kind of problem.
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Jim Smith avatar
I have tried a few different values but at the moment they are both set to 0.9x.
Jim Smith avatar
ST-4 didn't help. Similar poor results to pulse guiding. I have bought a Nevada PS-08 6-8A Regulated Linear Power Supply.
I will use that instead of my batteries and see if that helps.