I have the same problem, but on a Sky Sensor 2000 PC.
It was working well last November before the clouds blanketed the winter sky.
Here is what the log has.
[2018-03-02T22:07:40.265 EST DEBG ][ org.kde.kstars.indi] - SkySensor2000PC : "Error reading RA/DEC. "
[2018-03-02T22:07:46.271 EST DEBG ][ org.kde.kstars.indi] - SkySensor2000PC : "Error reading RA/DEC. "
It made some operations intermittent. For example, you tell it to slew, and it would not respond. Or it slews then the slew never completes.
Going into picocom, I typed the :GD# and :GR# commands manually:
:GD#+00�51:57#
:GR#04:16:59#
The response for GD has non ASCII characters in it:
$ hd
:GD#+00�51:58#
00000000 3a 47 44 23 2b 30 30 ef bf bd 35 31 3a 35 38 23 |:GD#+00...51:58#|
So hex ef bf bd, but that was via copy/paste.
What can one do to troubleshoot this further?