Considerations When Saving Plc Data - Siemens SINUMERIK 840Di Manual
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06.03
14.3
Considerations when saving PLC data
Original image
Instantaneous
image
Inconsistent
image
Siemens AG, 2003. All rights reserved
SINUMERIK 840Di Manual (HBI) – 06.03 Edition
When creating a series machine start-up file that contains PLC data, the PLC
image that is saved during this process is dependent on the status of the PLC at
the time of creation.
Depending on the status of the PLC, the following PLC images result:
– Original image
– Instantaneous image
– Inconsistent image.
The original image of the PLC is represented by the PLC data immediately after
loading the S7 project into the PLC.
Operating sequence:
1. Set the PLC to the operating status STOP
2. Load the appropriate S7 project into the PLC using the SIMATIC Manager
STEP7
3. Create a series machine start-up file with PLC data
4. Set the PLC to the operating status RUN.
If you cannot use the procedure described above, you can use the following
alternative procedure to save an original image:
Operating sequence:
1. Set the PLC to the operating status STOP
2. Archive the PLC data
3. Set the PLC to the operating status RUN.
An inconsistent image results if a series machine start-up file with PLC data is
created and the PLC is in the status RUN (cyclic operation).
The data blocks of the PLC are saved at different times with contents that under
certain circumstances may meanwhile have changed. This may result in a data
inconsistency that after copying the data backup back into the PLC may under
certain circumstances result in PLC stop in the user program.
Notice
The creation of a series machine start-up file with PLC data while the PLC is in
the RUN status (cyclic operation) may result in an inconsistent PLC image in
the series machine start-up archive.
After this series machine start-up file has been copied back, this data inconsis-
tency in the PLC user program may under certain circumstances result in the
stop of the PLC.
14 User Data Backup/Series Machine Start-Up
14.3 Considerations when saving PLC data
14-453
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