Siemens SINUMERIK 840DE SL - 2.4.5 Buffered actual value

Detailed Description
2.4 Referencing with incremental measurement systems
Reference Point Approach (R1)
Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0
2-19
2.4.5 Buffered actual value
Automatic referencing
Buffering the actual value enables "Automatic referencing" to be performed. With automatic
referencing, machine axes with incremental measuring systems do not have to repeat the
reference point approach in order to reference the measuring system following situations
when the status of these axes is "Non-referenced". For example, this is the case after:
• POWER OFF/ON
• "Parking" selected
DB31, ... DBB1.5/1.6 (position measuring system 1/2) = 0
DB31, ... DBB2.1 (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.
Warning
The machine axis must not be moved mechanically while the measuring system (encoder) of
the machine axis is switched off (POWER OFF, axis "parked" etc.). This must be supported
by the machine manufacturer with such measures as holding brakes, etc., and ensured by
the user. Otherwise the actual value system of the machine axis will no longer be
synchronized resulting in danger to personnel and machine.
Precondition for automatic referencing
At the time that automatic referencing occurs, e.g., after a POWER ON, when "parking" of
machine axis is deactivated again, 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.