It seems like I've found a bug with the PPEC control panel tab for EQMod and wondering if anyone else can replicate it.

It starts by doing something logically pretty stupid, but that's why we have testers I suppose - and that is enabling PPEC before training it.

To be clear is *HAD* trained the PPEC module, but then upgraded the motor firmware on my EQ8-R (trying to solve a different PPEC behaviour problem/possible bug) - when I clicked on "turn PPEC on" the driver crashed and kstars sessions terminated.

This is consistent with behaviour that I saw with my new EQ6-R and the EQ8-R when it was out of the box - in both cases I tried turning on PPEC without training and it crashed the driver.

The workaround is pretty dimple and obvious - train before using, but the behaviour seems incorrect to say the very least.

Is it just me?

The stupid guy who wrote the stupid indi-eqmod driver simply has no direct way to know if the mount has been trained or not. This may (and should) be stored in the motor controller memory but if ever it is, I do not know how to retrieve that information. Storing that info into the file system of what runs the driver is not really a solution, because as you said, what if you reflash the motor controller firmware ?
The reason why it crashes now is that the firmware returns a different code than before when starting PEC without training, which suggests that the info is now stored in the motor controller memory.
The same stupid guy would like to apologize that he has not thought that firmware may vary and has not enclosed that PEC On switch code with an appropriate try/catch clause. But is is well known here that this stupid driver is also highly unsafe. If I remember, this driver is even not capable to check if it is run against the right indi core dynamic library. What a pity...

LOL! Seriously, we're super grateful that it does all teh amazing things that it does.

I personally blame the equipment vendors for not publishing better API and documentation - they still think like hardware companies and not software companies.

Again, thanks for a product my imaging relies on every day!

I don't think it is fair of you to blame the equipment manufacturers because you are not using their published interface, you are using an internal interface that they only intend to be used for communication with their hand control.

Skywatcher has published the motor firmware protocol some years ago, it is still on their official site. I don't think they would sell so many mounts if you were not able to control the mount directly without using the hand controller. I believe they don't want to invest in software, because open source do that for them, customers may build the software they wish.