Siemens SINUMERIK 840D sl Function Manual page 1688

Detailed Description
2.5 Programming
Constant cutting rate setting
Constant cutting speed specifications from part program, FC18 or synchronized actions are
programmed in setting data:
SD43200 $SA_SPIND_S
and always programmed from the usual sources.
Read SD43202
The constant cutting speed is read from setting data:
SD43202 $SA_SPIND_CONSTCUT_S [m/min] or [feet/min]
with the positive edge of the start signal:
DB31, ... DBX30.1 (Spindle start CW)
and
DB31, ... DBX30.2 (Spindle start CCW).
Note
Rewriting of the setting data is not activated until the next positive edge of the start signals:
DB31, ... DBX30.1 (Spindle start CW)
and
DB31, ... DBX30.2 (Spindle start CCW)
for the current spindle speed.
The content of the setting data is only accepted with the next spindle start signal.
Supplementary condition
To ensure that constant cutting rate settings are active, the spindle concerned must be a
master spindle in the channel handling the spindle.
This condition is met when NC/PLC IS:
DB31, ... DBX84.0 = 1 (Constant cutting rate active)
is set on the axial VDI interface.
Writing from the part program
When writing from the part program, the value for the constant cutting rate is interpreted as
follows:
if G710 is active in the 12th G Group:
if G700 is set in the 12th G Group:
Regarding G70, G71 and the specification of external (HMI), the setting in the machine data:
MD10240 $MN_SCALING_SYSTEM_IS_METRIC
determines the interpretation of the specified values.
Further explanations regarding metric/inch measuring system can be found under:
Literature:
/FB1/ Function Manual, Basic Functions; Speeds, Setpoint-/Actual Value System, Control
(G2)
78
Metric
inch as [feet/min]
Basic logic functions: Spindles (S1)
Function Manual, 11/2006, 6FC5397-0BP10-2BA0