Status Words Seven To Nine (Stw07-Stw09) - Siemens SIMATIC TI525 Hardware And Installation Manual

4.5.2 Status Words Seven to Nine (STW07–STW09)
STW07 gives the absolute address of the first error encountered while
attempting to program the EEPROM. The value given is the memory address of
the EEPROM memory.
STW08 shows the checksum calculated from the RLL program stored in the
EEPROM. The checksum is a numerical calculation based on your RLL
program only. When you copy a program to several EEPROMs, you can check
STW08 for every EEPROM to verify that the information contained in each is
identical.
Identical RLL programs and identical I/O configurations
programmed in different machines may yield different
checksums due to internal storage differences.
STW09 shows the checksum generated from the EEPROM. The checksum is a
numerical calculation based on all data stored in the EEPROM, including your
RLL program and information contained in the I/O configuration memory.
When you copy a program to several EEPROMs, you can check STW09 for each
EEPROM to verify that the information contained in each is identical.
Permitting a PLC to execute an EPROM/EEPROM
program without first checking the program may result
in injury to personnel and damage to equipment due to
unexpected operation by the PLC. If you are not
absolutely certain that the EPROM/EEPROM program
is correct, disconnect all I/O modules and the IOCC (if
necessary) from the base before you power up.
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EPROM/EEPROM OPERATION
NOTE
WARNING
4-11
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