Protection Checksum - Siemens Sinumerik 840D sl Function Manual

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8.5

Protection checksum

Checksums are generated using this MD in order to detect falsification of the SI--
relevant machine data checked in the acceptance test.
In order to provide users with the most accurate information as possible about the
area of the safety relevant parameterization in which a discrepancy has occurred
between the reference and actual checksum, the machine data and the associated
checksums are subdivided into:
S Machine data that are parameterized using the axis--specific SI functionality
(refer to Chapter. 8.1.1)
=> $MA_SAFE_ACT_CHECKSUM[0...2]
S Machine data that are parameterized using the general and NCK--specific SI
functionality (refer to Chapter. 8.1.1)
=> $MN_SAFE_GLOB_ACT_CHECKSUM[0...3]
There are machine data fields, which are independent of one another, for these
two machine data groups, in which the checksums are saved.
These two groups are subdivided into various machine data, which in turn are used
to calculate independent checksums. Each checksum change is displayed with its
own alarm message. This means that using the alarm number alone, the user can
identify which function area should be especially carefully assessed in the sub-
sequently required function or acceptance test.
Modular machine concepts are supported by this distribution.
The value of the checksums $MN_SAFE_GLOB_ACT_CHECKSUM[0...3] and
$MA_SAFE_ACT_CHECKSUM[0...2] is re--calculated for various events:
S When the control boots
S Machine control panel reset
S PI service "_N_CRCSMD"
A comparison between the MD values $MN_SAFE_GLOB_ACT_CHECK-
SUM[0...3] / $MA_SAFE_ACT_CHECKSUM[0...2] and the expected values for the
checksums in MD $MN_SAFE_GLOB_DES_CHECKSUM[0...3] /
$MA_SAFE_DES_CHECKSUM[0...2] is only performed when the control boots, a
discrepancy between the values is displayed using one of the alarms mentioned
below.
In this case, it is necessary to confirm the actual checksum by copying this value
into MD $MN_SAFE_GLOB_DES_CHECKSUM[0...3] /
$MA_SAFE_DES_CHECKSUM[0...2] and rebooting the control.
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SINUMERIK 840D sl/SINAMICS S120 SINUMERIK Safety Integrated (FBSI sl) - - 10.2015 Edition
Data Description
8.5 Protection checksum
8-497