Buffered Actual Value - Siemens SINUMERIK 828D Function Manual

15.5.6.1

Buffered actual value

Automatic referencing
By buffering the actual value, "automatic referencing" is enabled, which does not require machine axes with
incremental measuring systems, after situations in which they are in the "Not referenced" condition, to traverse
back to the reference point for referencing of the measuring system. For example, this is the case after:
• POWER OFF/ON
• "Parking" selected:
DB31, ... DBX1.5 / 1.6 (position measuring system 1/2) = 0
DB31, ... DBX2.1 (servo enable) = 0
If the function is active, referencing is performed without axis motion by synchronizing the actual value system of
the machine axis to the last valid actual value. The actual value is buffered in a retentive memory area of the
control even after POWER OFF.
Precondition for automatic referencing
At the time of automatic referencing (e.g. after POWER ON, "Parking" of the machine axis is again deselected,
etc.), the encoder status of the active measuring system of the machine axis must have the value 2.
MD34210 $MA_ENC_REFP_STATE = 2
That is, the encoder is referenced, an exact stop is reached, and automatic referencing is active the next time the
encoder is activated.
The following conditions must be fulfilled:
• "Automatic referencing" is assigned for the measuring system (encoder):
MD34210 $MA_ENC_REFP_STATE = 1 (Encoder status = 1)
Automatic referencing enabled, but encoder not yet referenced or exact stop not reached.
• The measuring system has already been successfully referenced with reference point approach.
This is identified by the NC by changing the encoder status from 1 to 2:
MD34210 $MA_ENC_REFP_STATE = 2 (Encoder status = 2)
Encoder is referenced, an exact stop is reached, and automatic referencing is active the next time the
encoder is activated.
• The machine axis was disabled in "Exact stop fine" status.
Note
Within the scope of actual value buffering, the following axis specific interface signal is
evaluated:
DB31, ... DBX60.7 (Position reached with fine exact stop)
The actual values of machine axes that do not use the signal cannot be buffered.
Basic Functions
Function Manual, 09/2011, 6FC5397-0BP40-2BA0
15.5 Referencing with incremental measurement systems
R1: Reference point approach
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