Siemens SINUMERIK 840D sl Function Manual page 88

B3: Distributed systems - 840D sl only
3.2 NCU link
MD10050 $MN_SYSCLOCK_CYCLE_TIME
Note
Manual alignment across several communications buses
If several isochronous communication buses (PROFIBUS 1 ... n, PROFINET 1 ... m) have
been configured on an NCU, the same DP cycle time in STEP 7 HW Config must be set for
each communication bus.
Depending on the position control cycle clock
For the SINUMERIK 840D sl, the ratio between the basic system cycle clock and the position
control cycle clocks is fixed (1:1) and cannot be changed. Because only certain position control
cycle clocks can be set for the NCU link, only these position control cycle clocks can be set
as the basic system cycle clock or DP cycle time. See the next paragraph "Position control
cycle clock".
Position control cycle clock
The position control cycle clock is set as a ratio to the basic system cycle clock. For the
SINUMERIK 840D sl, the ratio is fixed (1:1) and cannot be changed. The current position
control cycle clock is displayed in the machine data:
MD10061 $MN_POSCTRL_CYCLE_TIME
Note
Permitted position control cycle clocks
For the NCU link, depending on the number of NCUs in the link group, only the following
position control cycle clocks [ms] are set:
● 2 NCU: 2.0, 2.5, 3.0, 3.5, 4.0
● 3 NCU: 3.0, 3.5, 4.0
See Section "Configuration (Page 90)".
Interpolator cycle clock
The interpolator cycle clock is set as a ratio of the basic system cycle clock. The setting is
made via the following machine data:
MD10070 $MN_IPO_SYSCLOCK_TIME_RATIO
The actual interpolator cycle clock is displayed in machine data:
MD10071 $MN_IPO_CYCLE_TIME
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Function Manual, 10/2015, 6FC5397-1BP40-5BA3
Extended Functions