Hi I have been using the internal guider mostly, but want to try out phd2.
I have the equipment connected (indi mount->Eqmod, indi camera -> QHY) and this  seems to work ok. However I sometimes get warning in Ekos PHD2: Please set CCD and telescope parameters in PHD2, Pixel Scale is invalid.

Also I cannot change from px to arcsec graphs - I presume this means phd2 doesn't seem to know the focal length of my guide scope ?

However when I look at INDI Options panel in phd2 I can see it has picked up the correct telescope profile with the the correct focal lengths and apertures.
Also in the INDI Options-> Guide Camera -> Image info  I see the correct pixel sizes and chip dimensions are picked up from INDI correctly.
Do I need to set some parameters in phd2 ? 
I was presuming that if I set the correct indi drivers in phd2 (Eqmod and QHY) then it would automatically
pick up everything from INDI - which it may be doing but I'm not entirely sure.

Sounds like you need to set the guide scope focal length in the PHD2 brain
 

Hi Ken.
Excellent. Many thanks. Not sure why it doesn't do this automatically since phd2 already has this data from INDI.
Anyhow I've set set that as you described and now I'm getting arcsecs rather than just pixels.
Cheers,
Nick

PHD2 only gets the camera data from INDI and that does not include the focal length of the guide scope. Could be worth an enhancement request in PHD2 to allow the server interface to receive focal length from the client but that would also require a change in EKOS to send it.

It's worthwhile getting the true focal length of your guide scope by using the plate solver. Don't rely on manufacturer specifications for the most accurate figures.
By doing so, you'll get a more accurate measurement of the RMS.

Hi Ken. yes I agree. It does seem a bit silly that you can see the focal lengths in phd2 Eqmod info but it then needs setting elsewhere.

Thanks Andrew. That's worth knowing. My FL's are same as from platesolve ( I used Ekos stellarsolver in the past they turn out the same
as specs).