That sounds like a motor load detecting issue. I’m not entirely sure if my knowledge on how express devices are homing is still up to date as there were some changes recently, also I can’t tell the difference of
STALL SENSIVITY and
MAX MOTOR LOAD for sure. @RickCarlino could maybe know something about those, or is it rather something for Rory/Gabriel?
What probably happens, is that your motor moves into negative direction until a high motor load (probably
MAX MOTOR LOAD parameter) is detected. Then it moves a small distance into the other direction followed by another move into negative direction until the motor load is reached again.
MAX MOTOR LOAD set over 100% sounds like a mistake to me, as the motor could never go over 100% (right?) which always prevents the software from detecting the stall situation which is only detected by motor load. Check the motor load on a normal movement, I’d say it should be below 85%. Then set the parameter
MAX MOTOR LOAD like 10% higher and see how it behaves. I hope that helps, thats how I would start.
You are most likely referring to the parameter
NEGATIVE COORDINATES ONLY. This parameter does not affect the homing cycle for a good reason. Imagine your bot restarted while the X-axis for example is not at home. When searching for the home position it has to go into negative direction/coordinates to find it. This paramater only prevents you from moving manually into negative values and is usually needed for mirrored axes (Z-axis for example).
Just to make sure, your parameter to enable limit switches is not enabled right?