SharpCap Pro and Celestron AVX Mount

[TheAstrophotographer]

Robin,

OK, tonight was finally the first night I was able to use my Celestron AVX Mount with NexStar 8SE and SharpCap Pro 4.1. In hardware for the mount, I am using the Celestron Device Hub and am getting a weird error I have never seen before:

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Key is the the hub is selecting Celestron Unified Driver 6.1.7350:

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So, now I got the following error when I tried to change the capture area from 3008x3008 to any other value and I got the following error:

E5BA1EC4-6228-490C-9F28-9B9546630F9B_4_5005_c.jpeg (88.16 KiB) Viewed 934 times

That said, I pushed ignore and continued to work on but not sure what was happened?

So, I am wondering if I should just use Celestron Unified Driver 6.1.7350 directly rather than the Hub but I am wondering what will happen if I start using another software like PHD2 which would use the same driver as I have heard that without the direct use of the Hub there also maybe be issues.

Would appreciate any help you can provide.

Thanks,

Edmund

[admin]

Hi Edmund,

the message looks as though it is indicating some sort of inconsistent state within the ASCOM driver itself (the Celestron Unified driver) - the driver is reporting that it is connected to the hardware, but actually it has somehow closed the serial port connection internally, so when it tries to send a command to the driver, an error occurs.

I suspect that this is not really much to do with changing resolution - I think that the driver has somehow closed the port in the background, which means that SharpCap will be failing to get updates on position (alt/az/ra/dec) from the driver *before* the resolution change. However, SharpCap doesn't pop up a big error box when that happens, it just logs the errors to the log and after a while gives up trying to get the new status of the mount. However, when you change resolution, that may trigger sending a command like one to ensure the tracking is in the desired state to the mount, and that *does* get you the error box.

It's certainly worth trying without the device hub to see if that helps. If you are connecting to the mount from other software too (like PHD or a planetarium), it would be good to test with that other software not running to see if it is related to multiple connections.

cheers,

Robin

[TheAstrophotographer]

Robin,

Per information from Celestron, your assumptions are correct that this error is not a SharpCap issue.

It seems that that the message occurs when the COM port connection to the mount is no longer open at the driver level as discussed.

They indicated that this can happen if the mount was connected through more than one program at the same time, if the driver was not the first item to establish the connection, or if the connection was interrupted and the software did not reconnect.

I guess from the mount side, the AVX does not close the port on its own.

The most common cause is simply that the COM port was already in use or was not opened cleanly by the application. This is odd because the use of hub is specifically for the purpose of using multiple programs since I am aware that the drive alone does have this issue.

I guess for a stable connection, the mount should be connected through a single ASCOM driver instance (either the Celestron Unified driver or Device Hub), and only one application should have access to that connection at a time. Both drivers are supported; the important part is that only one is being used for the connection. I guess my question would be what is the purpose of the hub?

Since the error appears at the software/driver level rather than from the mount, my next step is, as you suggested, to try connecting using only the Celestron ASCOM driver with no other applications open, and confirm that the COM port opens normally before starting SharpCap.

As you know the platform was just updated to 7.1 and they indicated that the ASCOM Platform does not cause the port to close, but they suggested that if the same issue appears when using the driver alone, then reinstalling the ASCOM platform and the Celestron driver would be the recommended step.

Thanks,

Edmund

[admin]

Hi Edmund,

glad to hear that you are collecting the info needed to hopefully get to the bottom of this issue.

The ASCOM Device hub is designed to allow sharing of an ASCOM driver between applications when the ASCOM driver itself wasn't built with this option available. If you are doing this then *every* application you are using should be connecting via the Device Hub - having some connect via the hub and some directly is asking for trouble. When you are using the hub, the ASCOM driver should be essentially unaware that multiple applications are sending it commends, since it just sees commands relayed via the device hub (which takes care of things like stopping multiple commands at once, etc). It should 'just work' - in theory.

cheers,

Robin