Galil DMC-1700 Manual De Usuario

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DMC-1700/1800 
Chapter 6  Programming Motion  •  129 
Homing 
The Find Edge (FE) and Home (HM) instructions may be used to home the motor to a mechanical reference.  This 
reference is connected to the Home input line. The HM command initializes the motor to the encoder index pulse in 
addition to the Home input.  The configure command (CN) is used to define the polarity of the home input. 
The Find Edge (FE) instruction is useful for initializing the motor to a home switch.  The home switch is connected 
to the Homing Input.  When the Find Edge command and Begin is used, the motor will accelerate up to the slew 
speed and slew until a transition is detected on the Homing line.  The motor will then decelerate to a stop.  A high 
deceleration value must be input before the find edge command is issued for the motor to decelerate rapidly after 
sensing the home switch.  The Home (HM) command can be used to position the motor on the index pulse after the 
home switch is detected.  This allows for finer positioning on initialization.  The HM command and BG command 
causes the following sequence of events to occur. 
Stage 1: 
Upon begin, the motor accelerates to the slew speed specified by the JG or SP commands.  The 
direction of its motion is determined by the state of the homing input.  If  _HMX reads 1 initially, 
the motor will go in the reverse direction first (direction of decreasing encoder counts).  If _HMX 
reads 0 initially, the motor will go in the forward direction first.  CN is the command used to 
define the polarity of the home input.  With CN,-1 (the default value) a normally open switch will 
make _HMX read 1 initially, and a normally closed switch will make _HMX read zero.  
Furthermore, with CN,1 a normally open switch will make _HMX read 0 initially, and a normally 
closed switch will make _HMX read 1.  Therefore, the CN command will need to be configured 
properly to ensure the correct direction of motion in the home sequence.  
Upon detecting the home switch changing state, the motor begins decelerating to a stop. 
Note: The direction of motion for the FE command also follows these rules for the state of the 
home input. 
Stage 2: 
The motor then traverses at 256 counts/sec in the opposite direction of Stage 1 until the home 
switch toggles again.  If Stage 3 is in the opposite direction of Stage 2, the motor will stop 
immediately at this point and change direction.  If Stage 2 is in the same direction as Stage 3, the 
motor will never stop, but will smoothly continue into Stage 3. 
Stage 3: 
The motor traverses forward at 256 counts/sec until the encoder index pulse is detected.  The 
motor then stops immediately.  
The DMC-1700/1800 defines the home position as the position at which the index was detected 
and sets the encoder reading at this point to zero.