Siemens S7-1200 System Manual page 384

Extended instructions
8.7 Recipes and Data logs
A data log file is created with a pre-determined fixed sized based on the RECORDS and
DATA parameters. The data records are organized as a circular log file. New records are
appended to the data log file, until the maximum number of records that is specified by the
RECORDS parameter is stored. The next record written will overwrite the oldest record.
Another record write operation will overwrite the next oldest data record and so on.
Memory resource usage:
● The data logs consume only load memory.
● There is no set limit for the total number of data logs. The size of all data logs combined
is limited by the available resources of load memory. Only eight data logs may be open at
one time.
● The maximum possible number for the RECORDS parameter is the limit for an UDint
number (4,294,967,295). The actual limit for the RECORD parameter depends on the
size of a single record, the size of other data logs, and the available resources of load
memory. In addition, Excel limits the number of rows allowed in an Excel sheet.
Note
Data log creation execution must be complete, before starting a data log write operation
• DataLogCreate and DataLogNewFile log file creation operations extend over many
program scan cycles. The actual time required for the log file creation depends on the
record structure and number of records. Your program logic must monitor and catch the
DONE bit's transition to the TRUE state that signals the completion of a log file creation. If
a DataLogWrite instruction is executed before a data log creation operation is complete,
then the write operation will fail to write a new data log record as expected.
• In certain situations when a very fast program scan is running, data log creation can take
an extended time. If the long creation time is too slow, you should ensure that the
checkbox for the Enable minimum cycle time for cyclic OBs is active, and the minimum
cycle time is set to one ms or greater. Refer to Configuring the cycle time and
communication load (Page 97) for more information.
Note
The DataLogNewFile instruction copies an existing data log's record structure
If you want to prevent overwriting any data records, then you can use the DataLogNewFile
instruction to create a new data log based on the current data log, after the current data log
has stored the maximum number of records. New data records are stored in the new data
log file. The old data log file and record data remain stored in flash memory.
Table 8- 160 Values of ERROR and STATUS
ERROR STATUS
(W#16#....)
0 0000
0 7000
0 7001
0 7002
384
Description
No error
Call with no REQ edge: BUSY = 0, DONE = 0
First call with REQ edge (working): BUSY = 1, DONE = 0
N call (working): BUSY = 1, DONE = 0
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S7-1200 Programmable controller
System Manual, 03/2014, A5E02486680-AG