Programming 
Page D-152  890CS Common Bus Supply - Frames B & D; 890CD Common Bus Drive and 890SD Standalone Drive - Frames B, C & D 
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ZERO SPEED 
SETUP::MOTOR CONTROL::ZERO SPEED 
This function block detects when the motor speed is at or close to zero. HYSTERESIS and THRESHOLD are user-definable. 
Parameter Descriptions 
HYSTERISIS 
PREF: 85.01  Default: 0.10 %  Range: 0.00 to 300.00 % 
Provides a hysteresis band about which the outputs are stable. 
IF the hysteresis value is >= to the Threshold 
THEN the level is set to 2 x the hysteresis value and the Off level is set to zero, 
ELSE the On level = Threshold + Hysteresis and the Off level = Threshold - Hysteresis. 
THRESHOLD 
PREF: 85.02  Default: 0.50 %  Range: 0.00 to 300.00 % 
The nominal level below which the outputs are set. 
AT ZERO SPD FBK 
PREF: 85.03  Default: TRUE  Range: FALSE  / TRUE 
Speed feedback. TRUE when at zero speed feedback, as defined by THRESHOLD and HYSTERESIS. 
IF (abs(speed feedback)) > On Level at zero speed = FALSE 
ELSE if (abs(speed feedback)) <= Off Level at zero speed = TRUE 
ELSE at zero speed is unchanged 
AT ZERO SPD DMD 
PREF: 85.04  Default: TRUE  Range: FALSE  / TRUE 
Speed demand. TRUE when at zero speed demand, as defined by THRESHOLD and HYSTERESIS. 
AT STANDSTILL 
PREF: 85.05  Default: TRUE  Range: FALSE  / TRUE 
TRUE when both AT ZERO SPD FBK and AT ZERO SPD DMD are TRUE.