Speed Control Motors

• What applications are BLDC motors best used for?
• What is the feedback system used for speed control on the DSC and US2 AC speed control series?
• I am using the DSC series and an alarm code beginning with AL is displayed on the front panel of the speed controller. What is the meaning of this alarm code?
• Can I set acceleration/deceleration on the BMU series?
• I connected the external operation signal FWD input/REV input to the BMU series and turned the input ON, but it doesn't work. Why doesn't it work?