Position Monitoring - Siemens SINUMERIK 840C Installation Instructions Manual

10 Axis and Spindle Installation 06.93
10.4.1 Drive optimization
10.4.1.6

Position monitoring

Coarse exact stop and fine exact stop tolerance ranges (NC MD 204* and 208*)
The approached position is checked. In automatic mode, the next block is not started if the
following error exceeds the value entered in NC MD 204* to 208*.
Setting
The positioning accuracy depends on the quality of the position control and speed control
loops.
The normal deviation is ascertained by observing the following error at zero speed (i.e. in the
"at rest" state).
Depending on the customer's requirements and the positioning accuracy attained, the
specified value should lie in the range from 10 µm to 50 µm, but should be at least double the
maximum following error deviation at zero speed.
Zero-speed monitoring (NC MD 212*)
The machine manufacturer must try to keep the position deviation to a minimum, i.e. under the
exact stop tolerance range set in NC MD 204* to 208*. The value specified for zero-speed
monitoring (NC MD 212*) should be approximately double that entered in NC MD 204* to 208*.
Alarm 112* is triggered if one of the axes is forced out of position (clamping active and
cancellation of the servo enable signal) at zero speed (after the time set in NC MD 372* has
elapsed).
Positioning is monitored in order to ensure that an axis reaches its position within the specified
time period (in dependence on K factor, acceleration, ...). The monitoring data are set in NC
V
MD 212* and NC MD 372*. A detailed description is given under NC MD 372*.
10–30
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SINUMERIK 840C (IA)