B–64113EN–1/01
15. PMC CONTROL FUNCTION
999
(2)Switching from torque control to position control
(canceling torque control mode)
Torque control mode is canceled when any of the following conditions
is satisfied:
1) The reset signal ECLRg is brought to “1”.
2) A servo alarm is issued.
3) An OT alarm is issued on the torque control axis.
4) An emergency stop occurs.
5) The servo motor is turned off by the servo off signal ESOFg.
a. Timing for canceling torque control
When torque control by the PMC controlled axis is canceled,
follow–up may or may not be performed, depending on the setting
in the TRF bit (bit 4 of parameter No. 1803). If follow–up is
suppressed, the torque control mode signal TRQMx immediately
goes “0” when a condition to cancel torque control is detected.
Then, position control mode is selected. The execution terminates
when the position error enters the effective range. If follow–up is
performed, the torque control mode signal TRQMx goes “0” when
a condition to cancel torque control is detected. Then, follow–up
starts. When the position error falls below or equals the cancel limit
value specified in parameter 1886, position control mode is
selected. The execution terminates when the position error enters
the effective range.
b. Command after torque control mode is canceled
When torque control mode is canceled, normal position control
mode is selected. In torque control mode, the position is managed,
and the machine coordinates are not displaced. The workpiece
coordinates, however, are shifted from the machine coordinates.
The shift must be canceled by specifying the command for setting
the workpiece coordinate system or similar function.
CAUTION
1 If the torque control axis may be moved in torque control
mode, the follow–up parameter TQF (bit 4 of parameter No.
1803) must be set to “1”.
2 If torque control mode is canceled while the torque control
axis is moving, the return to position control mode causes
a mechanical impact. A faster movement causes a greater
impact. To cancel torque control mode, decelerate or stop
the movement in advance.
3 When specifying the torque control command after a
manual reference position return is completed, set the feed
direction selection signal to “0” in advance. Alternatively,
select a mode other than manual reference position return
mode in advance.