Siemens SINUMERIK 840D sl Function Manual page 184

Several Operator Panels on Several NCUs, Distributed Systems (B3)
2.12 NCU link with different interpolation cycles
Abbreviations and terms
NCU-A, NCU-B
NCU-U
Position control cycle i
Position control cycle j
IPO cycle m
IPO cycle n
Link cycle m
S1-S8
Z1-Z8
X1-X8
X9
TD
Cycles
The IPO cycle m is an integer multiple of IPO cycle n.
Position control cycle i may be greater than fast IPO cycle n.
Slow IPO cycle m is used as a communication cycle between NCU-A/NCU-B and NCU-U.
Spindle speed
The part program manufacturer must first perform an OFFLINE calculation to ascertain the
maximum spindle speed to program so that the axes (especially the X axis) are not
overloaded when accelerating. If this maximum speed is incorrect, the spindle speed is
reduced at points where one of the participating axes would be overloaded. This in turn has
a bearing on contour precision and should therefore be avoided.
Contour deviations
Spindle decelerations/accelerations lead to deviations from the programmed contour
because the cycles of NCU-A/NCU-B and NCU-U have different lengths; therefore, the
acceleration processes should already be terminated before initiating eccentric contour
machining.
Axis assignments
Link axes may only be connected to NCUs that have the same IPO cycle as the link cycle.
Example: Axis X9 on the fast NCU-U in the diagram above cannot be interpolated as a link
axis by NCU-A or NCU-B. However, axis Z4 can be interpolated by NCU-A, NCU-B and
NCU-U.
184
NCUs with standard interpolation cycle
Eccentric NCU with fast interpolation cycle
"slower" position control cycle
"faster" position control cycle
"slower" interpolation cycle
"faster" interpolation cycle
Uniform link cycle from NCU-A to NCU-U
Spindles 1-8
Z axes 1-8
X axes for concentric machining via NCU-A/NCU-B
X axis for eccentric machining
On NCU-U channels are defined which drive the spindles
and Z axes of NCU-A/NCU-B as link/container axes and
interpolate the highly dynamic X axis with fast
interpolation and position control cycles.
Function Manual, 01/2008, 6FC5397-1BP10-3BA0
Extended Functions