Siemens SINUMERIK 840C - Manual (Page 226)

09.95 6 NC Machine Data (NC MD), NC Setting Data (NC SD)
6.4 Axis-specific MD 1 (axial data 1)
Backlash compensation 1st measuring system 220*
Default value Lower input limit Upper input limit Units
0 –16 000 16 000 units (MS)
Active on
NC Stop
In the case of axes with indirect measuring systems, mechanical backlash results in corruption
of the traversing path. When the direction is reversed, traverse is either shortened or extended
by the amount of backlash, depending on the design.
Positive backlash (normal case) Negative backlash
Actual encoder value ahead of real actual Real actual value (table) ahead of actual
value (table): Too little table travel encoder value: Too much table travel
Rack
Backlash
Table
Backlash
M
Encoder
Table
Encoder
The compensation value (amount of backlash) entered must be positive for positive backlash
and negative for negative backlash.
The control compensates the backlash specified in NC MD 220* (in all operating modes and in
all interpolation modes) each time the relevant axis changes its direction of travel.
Note:
As from SW 4, for 8 parameter sets
From SW 4 onwards interface signal "Reference point reached" is reset if MD 220* is
changed.
2nd software limit switch minus 228*
Default value Lower input limit Upper input limit Units
±99 999 999 ±0 99 999 999 units (MS)
Active on
NC Stop
1st software limit switch plus 224* Active on
NC Stop
3rd software limit switch plus 232* Active on
NC Stop
4th software limit switch minus 236* Active on
NC Stop
Default value
For 224*, 232* + 99 999 999
For 228*, 236* – 99 999 999
A software limit switch may be used in addition to the customary range limit switch (hardware
limit switch). The operator enters the absolute position of the positive range limit for each axis.
© Siemens AG 1992 All Rights Reserved 6FC5197- AA50 6–41
SINUMERIK 840C (IA)