Good news! The Firmware-Update has done its job. Synscan driver does anyhow still throw the serial timeouts, but the mount reacts without delay. Also, the Celestron GPS driver tells me that guiding is supported now and connects via PHD2.

I think, I will stay with this config then. The EQDir is a nice idea, but i think it is way easier to do all the alignment with the handbox instead of using the Raspi. It should only be needed for Guiding, which should work now!

Thanks
Tobi

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