Siemens SINUMERIK 880 SW 6 Planning Manual page 291

9 Axis/PLC Interface (DB 32)
9.2 Signals from axis
Note:
• The axis travels over the two adjacent reference marks with reference point approach
creep velocity (MD 284*). The axis is stopped when it reaches the second reference mark.
• To calculate the absolute axis position, the absolute encoder offset (offset between the
machine system and the linear scale, MD 396*) and the basic distance between the
reference marks are required (MD 1300*).
• MD 1808* indicates whether measuring system 1 or 2 is distance-coded (bit 4 and 5),
whether the absolute encoder runs in the same direction or in the opposite direction to the
machine system (bit 2) and whether the absolute encoder offset is valid (bit 3).
If the absolute encoder offset (bit 3 = 0) is invalid, referencing is still possible but the
signal REFERENCE POINT APPROACH is not set. You have to set bit 3 and reference
again.
• If two measuring systems are used on one axis, only one measuring system can be
distance-coded.
• If distance-coded reference marks are used, the function "zero monitoring" must be
switched off.
Application example:
Suppression of the start signal (NC START) if, for example, a parking axis is not synchronized
when it is activated.
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SINUMERIK 880 (PJ)