
B–63833EN–1/02
15. PMC CONTROL FUNCTION
883
The machine coordinate system selection command (EC0g to EC6g:
20h) performs absolute positioning to move the tool in rapid traverse to
a specified position on the machine coordinate system. This command
is used to move the tool to a position specifically defined for the machine,
such as the tool change position.
For a rotation axis, short cut rotation can also be specified. When using
this command for a T series, cancel the tool offset and the tool nose radius
compensation. For a M series, cancel cutter compensation, tool length
compensation, and tool offset.
The machine coordinate system must be set before attempting to use this
command. After turning on the power, return the tool to the reference
position either manually or by using G28. When an absolute position
detector is provided, returning the tool to the reference position is not
necessary because the tool position will be stored in memory.
When torque control is selected (EC0g to EC6g: 11h), the PMC
controlled axis can be subjected to torque control instead of position
control. In the torque control mode, the servo motor outputs the torque
specified by the NC.
(1)Switching from position control to torque control
a. Setting a torque control axis
Set the axis to be subjected to torque control in the TRQMx bit (bit
7 of parameter No. 2007). Also set the torque control axis in
parameter No. 2105 of the torque constant. The motor–specific
standard value is automatically set in this parameter when the
power is turned on with the DGPR bit (bit 1 of parameter No. 2000)
set to 0.
b. Position management in torque control mode
In torque control mode, choosing whether to perform follow–up
can be selected by setting the TQF bit (bit 4 of parameter No. 1803).
When follow–up is not performed, an integrated travel value (error
count) exceeding the value of parameter No. 1885 causes servo
alarm 423 to be issued. When torque control is switched to position
control, follow–up is always performed, even if follow–up
suppression is selected.
The CNC manages the position even in torque control mode. After
torque control is switched to position control, no reference position
return is necessary.
c. Traveling direction and speed in torque control mode
In torque control mode, the torque specified by the axis control data
signal is output. While there is no target of torque generation or
while the output torque falls below the specified torque, the
traveling direction is determined by the plus or minus sign added
to the torque data, as in position control. When the traveling speed
exceeds the specified speed, servo alarm 422 is issued.
d. Timing of switching to torque control
A mode is switched to torque control mode after the position error
enters the effective range (in–position state).
Machine coordinate
system selection
Torque control command