System Event Data Block Db254 - Siemens SIMATIC S5-95F Manual

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S5-95F
15.3

System Event Data Block DB254

The system event data block (DB254) is subdivided into several sections. These sections are
shown in Table 15-1. Purpose, contents and characteristics of these sections are discussed in detail
in the following sections.
Location in
the DB
DW 0 to 1
DW 2 to 33
DW 34
DW 35 to 36
DW 37
DW 38 to 55
DW 56
DW 57 to 60
DW 61 to 62
DW 63
DW 64 to 191
15.3.1 System Identification and ID Number Entries
Product Identification
Data word DW 0 in the system event DB of each basic unit contains the product identification code
"095F
". You must not change this code.
H
System ID Number
If your system comprises several S5-95Fs, each with its own user program, it is conceivable that
the wrong EPROM submodule might inadvertantly be plugged into the wrong PLC. To prevent such
a problem, a unique system ID number can be assigned to each S5-95F. The system ID number
must be entered in DB1 when the system parameters are initialized.
In failsafe systems, the operating system reads the system ID number from DB1 and enters it into
data word DW1 of the system event DB. From this point on, the S5-95F accepts only EPROM
submodules with this system ID number. You can erase the ID number via a manual overall reset.
Safety Note
When using the system ID number as security measure, remember that
The system ID number may not be zero
An overall reset sets the system ID number to zero.
EWA 4NEB 812 6210-02
Table 15-1. Structure of the System Event DB
Sections of the System Event DB (DB254)
Product identification and system ID number
Standard FBs loaded and their actual signature
Group info for responses to errors
Image of the passivated signal groups
Image of the error groups
Image for errors at inputs and outputs
Image for SINEC L1 errors
Unassigned
Error block counter and write pointer
Unassigned
Error entries with time stamp (a total of 16 error blocks of 8 data words
each)
Error Diagnosis and Elimination
15-3

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