Examples and tips
PROGRAMMING MANUAL
257
Revi
si
on 3.0
Origin search against hardware parts blocking movement
fig. 30
This origin search procedure performs origin search against a
physical object and mechanically blocks the movement. There are
no limit switches, no absolute position switch and no reference
pulses. The origin position is detected by detecting a particular
amount of torque against the blocking objects. An adequate torque
limit is required in order not to damage the mechanics during the
origin search process. The example for this homing procedure is
shown in the figure.
The program example that does this origin search sequence is
given below.
BASE(0)
DRIVE_CONTROL=11 'Monitor torque with DRIVE_MONITOR
SERVO=ON
WDOG=ON
SPEED=CREEP
REVERSE
WA(1)
WAIT UNTIL DRIVE_MONITOR < -100
'Wait for particular amount of applied torque
CANCEL
DEFPOS(0)
MOVEABS(10) 'This is necessary, otherwise the position
'is kept pushing the hardware limit of the
'machine and the motor trips by overload
moving part
I52E-EN-03.book Seite 257 Freitag, 29. Juni 2007 11:55 11