Strange focuser backlash behavior with NINA driver for Pegasus UPB Nightly #076

I have a consistent problem with the backlash operation with NINA’s own focus driver for the Pegasus UPB. It does not occur with Pegasus’s own utility, or using the Pegasus ASCOM driver with NINA or SGP. I can see what is happening by using a large backlash value and observing the rotating focus wheel of the telescope.

This is an intermittent issue that occurs with backlash set in EITHER the focuser settings on the equipment tab or in the auto focus settings on the options tab. I have it set on outward moves. It works some of the time but occasionally does not apply any backlash, or reverses a few times and applies a large offset and moves in too far. To test, I press the >> to move it outwards, observe the motion, wait for it to complete and press again… about 1 in 4 does not apply any backlash at all, or oscillates back and forth a few times before applying too much inward motion.

(I am aware that multiple backlash systems can interfere with each other and, in each case, I disabled all other settings so I was testing one at a time. This happens at the default motor speed and the lower speeds. I used the same settings for the ASCOM driver tests, which were 100% ok)

The focuser motion with the ASCOM control is smooth and clear to watch. The NINA control of the focuser is more jerky. I noticed that the Pegasus unit uses some form of microstepping and does have accel/decel controls in its interface. From past experience it occurred another possibility is a timing issue around ‘is moving’

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