Siemens SINUMERIK Series Function Manual page 84

B3: Distributed systems - 840D sl only
2.2 NCU link
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 85)".
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
Notes on setting
Cycle clock settings
It is recommended the following settings are made:
● The default 90% setting for the CPU time share of the NCK should be retained:
● The system cycle clocks must be set so that the average system utilization caused by the
Lowest cyclic communication load
The lowest cyclic communication load during the link communication results for a cycle clock
ratio of interpolator cycle clock to position control cycle clock of 1:1. With activated "Dynamic
Servo Control (DSC)" drive function, this is generally the most effective setting.
Disadvantage: No telegram repetitions are possible for the link communication.
84
MD10185 $MN_NCK_PCOS_TIME_RATIO
interpolator and the position controller does not exceed 60% in normal program
operation. As maximum value, 90% should be not be exceeded.
Note:
In special circumstances, maximum values > 100% can be displayed.
Function Manual, 03/2013, 6FC5397-1BP40-3BA1
Extended Functions