CB Set AT89C55WD chip port bit to low level   

Command	Command description	Controller response	Default mode (N/A - not available)	Service Mode (N/A - not available)
xCBy	Clear port bit. y: 22 = P2.2; 35 = P3.5; 7 = P0.7	-	Yes	Yes

SYNTAX    xCBy, where x - controller (axis) number.
PARAMETER y is port address of AT89C55WD chip. y= 0 if P0.0; y=14 if P1.4; y=37 if P3.7
Range 0...7, 10...17, 20...27, 30...37.
DESCRIPTION This command resets the port output bit (low TTL level).
Example: 1CB0 command sets to low level P0.0 output. It switches on (enables TA8435H chip) stepper motor current. The same makes xON command. 
RETURNS  none
REL. COMMANDS TB, SB
EXAMPLES: 5 cb25    ||   3cB 15   ||  2345CB0