Description Of Machine Data - Siemens Sinumerik 840D sl Function Manual

Data Description
8.1 Machine data for SINUMERIK 840D sl
8.1.2

Description of machine data

General information
General information about machine data and an explanation of their contents such
as units, data type, protective stage, effectiveness, etc. can be found in the follow-
ing references:
Reference:
10050
MD number
Default value: 0.004
Change becomes effective after: POWER ON
Data type: Double
Meaning:
Special cases, errors,...
corresponds with..
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SINUMERIK 840D sl/SINAMICS S120 SINUMERIK Safety Integrated (FBSI sl) - - 10.2015 Edition
/LIS1/ List Manual Machine Data SINUMERIK 840D sl
$MN_SYSCLOCK_CYCLE_TIME
Basic system clock cycle
Min. input limit: 0.000125
Protection level: 7/2
Basic clock cycle time of the system software
The clock cycle times of cyclic tasks (position controller/IPO) are set in a multiple of this
basic clock cycle. Apart from special applications in which POSCTRL_SYSC-
LOCK_TIME_RATIO is set to a value greater than 1, the basic clock cycle corresponds to
the position controller clock cycle.
For systems with PROFIBUS- -DP connection, this MD corresponds to the PROFIBUS- -DP
cycle time. When booting, this time is read out of the configuring file (SDP type 2000) and
written into the MD.
This MD can only be changed using the configuring file.
Note:
If this MD is reduced, then this can result in an automatic correction of
POSCTRL_CYCLE_DELAY, that cannot be undone at the next increase!
Details:
The basic clock cycle is an integer multiple (SYSCLOCK_SAMPL_TIME_RATIO) of units
of the clock cycle of the measured value sampling. When the system boots, the entered
value is automatically rounded to a multiple of this incrementing.
Note:
After a POWER OFF/ON, discrete timer division ratios may produce a value that is not an
integer of the input value.
e.g.
Entry =0.005s
after power OFF/ON =0.00499840
or
Entry =0.006s
after power OFF/ON =0.0060032
Max. input limit: 0.031
Unit: s
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