tl446 Right now it seems that the RA/DEC pulses are ignored by Skyhunter.

What are you selecting as the iOptron model for you mount?

The reason I ask is becuase of how pulse guiding works.

In the dawn of autoguiding, it was through the ST-4 port, pioneered by SBIG -- ST-4 was the model of one of their guide camera/system). People then realized that you could do the same thing (without building their own ST-4 interface) by sending a slew command for N milliseconds (this is why guide pulses are still specifies in milliseconds), with the slew rate set to 0.5 - 1.0 sidereal rate (1x sidereal rate produces a 15 arc second movement per 1000-millisecond pulse). The controlling computer would start a slew command, software time the N milliseconds, then send a stop-slew command.

Command latencies and process switching latencies would make guiding not as precise as one would like. So, mount manufacturers started to include an integrated a "slew/guide at rate R for N milliseconds" command (sometimes R is implicit) The timing is done quite precisely at the mount's motor.

The movement of mounts towards 115200 buad instead of 9600 baud is to mitigate command latencies. A typical slew command cound take 10 or more milliseconds at 9600 baud.

The reason I mention this is that IOptron had a couple of years ago added this timed slew command to their command instruction set of their higher end mounts (I haven't check lately if that has percolated to their cheaper mounts).

The other thing I do not know is if ZWO has started to use these newer commands, or are they still using the slews that are software timed in the ASIAIR. (I keep an eye open for other mounts, but do not track iOptrons.)

You can ask ZWO if they are now using those commands for the iOptron mount model that you have selected, and ask iOptron if your particular mount actually implements that command (and if it has been properly tested).

If the answer is yes for the first question, and no for the second question, you mount would naturally not autoguide, and would need the good old software timed commands.

If ZWO is not forthcoming with the information, you can actually find out yourself by using a USB protocol analyser (placed between the ASIAIR and the mount) to log all the commands sent by ASIAIR. You can use WireShark, or if you are on macOS, I had some years ago written a serial port tool that included a protocol analyzer: https://www.w7ay.net/site/Applications/Serial%20Tools/

You can then check the USB packets to see if ZWO had used commands that your mount's command protocol support. You should be able to request your mount's protocol document from iOptron.

Lots of people think they can use protocols for one mount model with another mount model, but most of the time, there will be some small incompatibility, and perhaps you have stumbled across one.

Chen

tl446 ASIairPro is sending seems to not be the one that Skyhunter is waiting

Yep, as I suspected. When it comes to autoguiding, your particular iOptron model is not compatible with command protocol of the iOptron model that you have selected. Basically, your mount is not supported by ASIAIR -- whoever told you that it does is leading you in a wild goose chase.

The interesting thing is that had the Cloudy Night person looked at the response from the commands, he should have also seen that the mount is returning an Error response if the mount does not grok a certain command.

ZWO is very sloppy with their coding, and I have seen other places where they ignored a error response for a device. If they had done their work correctly, ZWO could have warned with an error message that the mount is not compatible withthe protocol that they are using.

They could also have checked ahead of time (when first connecting to the mount)that the command protocol version is different from that they are coding to. Again, very sloppy work (wouldn't have lasted a day in the Silicon Valley which, like it or not, has "at will" employment).

At this point, all you can do is to look for another iOptron model that is more compatible with your mount -- but it may not be compatible for some other function. ZWO probably has never claimed yet that your mount is supported. Unless it is not beyond your capabilities to implement a mount proxy in a small Arduino processor that translates the commands that ZWO uses into commands that your mount understands; that would be what I would do.

For now, just consider your mount to be "not supported" by ASIAIR.

Chen