Galil DMC-2X00 user manual Homing

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 velocity profile generated is shown in Fig. 6.10.

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 command sequence HM and BG causes the following sequence of events to occur.

1.Upon begin, motor accelerates to the slew speed. The direction of its motion is determined by the state of the homing input. A zero (GND) will cause the motor to start in the forward direction; +5V will cause it to start in the reverse direction. The CN command is used to define the polarity of the home input.

2.Upon detecting the home switch changing state, the motor begins decelerating to a stop.

3.The motor then traverses very slowly back until the home switch toggles again.

4.The motor then traverses forward until the encoder index pulse is detected.

5.The DMC-2x00 defines the home position (0) as the position at which the index was detected.

Example

Instruction	Interpretation
#HOME	Label
AC 1000000	Acceleration Rate
DC 1000000	Deceleration Rate
SP 5000	Speed for Home Search
HM A	Home A
BG A	Begin Motion
AM A	After Complete
MG "AT HOME"	Send Message
EN	End
#EDGE	Label
AC 2000000	Acceleration rate
DC 2000000	Deceleration rate
SP 8000	Speed
FE B	Find edge command
BG B	Begin motion
AM B	After complete
MG "FOUND HOME"	Send message
DP,0	Define position as 0
EN	End

72 • Chapter 6 Programming Motion DMC-2X00