A customer has a line that is controlling the material movement without referencing the Motion outputs on the XL. Sometimes when the line halts, the Die appears to sit stationary at the end of its stroke and the Run output is stuck ON. When power is cycled the controller reports that the Die was in motion during power up.

It is believed that the controller is trying to return the Die to the home position. However, the Die is slowly traveling away from home at a speed that is slow enough to appear stationary.

Through code review it appears that it is possible for the function responsible for setting die return speed to use a negative line speed in calculations that expect a positive line speed. This would result in a negative velocity being provided or used and the die traveling away from home rather than towards home. The theory is that when this happens a very small negative velocity is being used or captured just as the line halts at times. Many lines have some backlash when they halt, which can result in a slight reversal in position/velocity as they settle to a stop which makes this theory plausible.

All calculations involved in the speed calculations have been analyzed. Any chance of a negative velocity being used have been eliminated. Additional protections have been added to ensure the Die Return velocity is between the Min and Max Die return velocities and that their polarity remains positive as assumed in the software.