Siemens sinumerik 840D sl Function Manual page 285

Synchronous monitoring
The synchronism of the gearbox is monitored in each interpolator cycle on the basis of the
actual values of the following and leading axes. For this purpose, the actual values of the
axes are computed according to the rule of motion of the coupling. The difference in
synchronism is the difference between the actual value of the following axis and the value
calculated from the leading axis actual values according to the rule of motion. The difference
in synchronism can be polled from within the parts program. See below.
Changes in the difference in synchronous traverse
The mass inertia of the axis systems during acceleration can cause dynamic fluctuations in
the difference in synchronous traverse. The difference in synchronous traverse is checked
continuously and the tolerance values in the machine data used to produce interface signals.
The difference in synchronous traverse is compared with the following machine data:
MD37200 $MA_COUPLE_POS_TOL_COARSE
and
MD37210 $MA_COUPLE_POS_TOL_FINE
Depending on the result of this comparison, the following signals are set:
NST "Synchronous travel fine" DB31, ... DBX98.0
and
NST "synchronous travers coarse" DB31, ... DBX98.1
Difference > .. TOL_COARSE
As long as the synchronous traverse difference is greater than the following machine data,
the gearbox is not synchronized and neither IS "Coarse synchronism" DB 31, ... DBX 98.1
nor IS "Fine synchronism" DB 31, ... DBX 98.0 is active.
MD37200 $MN_COUPLE_POS_TOL_COARSE
Instead, the following interface signal is displayed:
NST "synchronization running" DB31, ... DBX99.4
Difference < .. TOL_COARSE
As long as the synchronous traverse difference is smaller than the following machine data,
IS "Coarse synchronism" DB 31, ... DBX 98.1 is at the interface and IS "Fine synchronism"
DB 31, ... DBX 98.0 is deleted.
MD37200 $MN_COUPLE_POS_TOL_COARSE
Difference > .. TOL_FINE
If synchronous traverse difference is smaller than the following machine data, then NST
"synchronous traverse fine" DB31, ... DBX98.0 is at the interface:
MD37210 $MA COUPLE_POS_TOL_FINE
Special functions: Axis Couplings and ESR (M3)
Function Manual, 11/2006, 6FC5397-2BP10-2BA0
Detailed description
2.4 Electronic gearbox (EG)
65