Principle of Operation
Micro Automation Set 14 Entry ID 21062588
V2.0 05/18/05 14/35
Copyright © Siemens AG 2005 All rights reserved
Set14_DocTech_V2.0_en.doc
4.2 Receiving and archiving the data records in S7-200
Table 4-2
No. Function Comment
1.
The central processing unit of S7-200
“Backup” receives data of S7-200 “Basis”
in an input buffer.
2.
The structure of the data to be received is
emulated in the data block of S7-200
“Backup” using the “Data-Log” wizard. A
data record includes 20 data fields with
process value and time stamp.
3.
The “DAT0_WRITE” function block for
starting the archiving process provided by
the “Data-Log” wizard is called if all 20
data fields have been received and if
consistency is ensured.
4.
If the archiving process is started, the
“Data-Log” wizard writes the data records
from the data block into the 256 KB
memory cartridge. During each call a
new data record is added to the already
existing archive data. If the memory
cartridge is full, the oldest archived data
records are overwritten.
5.
Via the S7-200 Explorer integrated in
STEP 7 MicroWIN, the process values
with time stamp can e.g. be read via
Microsoft Excel and further processed.
Note
To show the functionality of data storage on the 256 KB memory
cartridge in this Micro Automation Set 14, data are frequently written to
the memory cartridge (approx. every 20 seconds). Due to the limited life
of approximately 1,000,000 write procedures of the memory cartridge,
longer backup intervals should be used for industrial use.
Start archiving process
Data available: OK
Consistency: OK
Module
55
78
98
78 98
55
DB1
55
78
98
Input buffer
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