3 – 664 HEIDENHAIN Service Manual iTNC 530
3.3.1 Position or servo lag monitoring
The axis positions are monitored by the iTNC as long as the control loop is closed.
The input values for position monitoring depend on the maximum possible following error (servo
lag). Therefore the input ranges for operation with following error and velocity feedforward are
separate.
For both modes of operation there are two range limits for position monitoring.
If the first limit is exceeded, the error message Positioning error is generated: The machine
stops.
You can clear this message with the CE key. An actual-to-nominal value transfer is then executed
for the respective axis.
If the second limit is exceeded, the error message Excessive servo lag in <axis> appears.
The control-is-ready signal output is reset. The EMERGENCY STOP chain is interrupted.
MP1410.x Position monitoring for the operation with velocity feedforward control (NC
stop)
MP1420.x Position monitoring for the operation with velocity feedforward control
(EMERGENCY STOP)
MP1710.x Position monitoring for the operation with following error (NC stop)
MP1720.x Position monitoring for the operation with following error (EMERGENCY
STOP)
Possible
causes of error
The list does not claim to be complete; ask your machine tool builder!
You may add your own experiences!
îš„ Blunt tool
îš„ Excessive machining feed rate
îš„ Spindle speed too low
îš„ Insufficient lubrication
îš„ General mechanical stiffness
îš„ Vibration load on the machine
îš„ With analog axes: excessive offset (drift), faulty tachometer or carbon brushes
îš„ Hardware error in the control loop
îš„ Scanning head loose
îš„ Encoder defective
îš„ Encoder cable defective
Difference between
position at switch-
on and shutdown
When the control is switched off, the actual position of the axes is saved with an absolute
encoder. During switch-on it is compared with the position values read by the encoder.
If the positions differ by more than the difference defined in MP 1146.x, a pop-up window
appears with both positions. The new position can be confirmed with a soft key. If it is not
confirmed, the error message Check the position encoder <axis> appears.
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