Siemens SIMATIC S7 System Manual page 299

Table 8- 132 Data types for the parameters
Parameter and type
REQ IN
ID In/Out
DONE OUT
BUSY OUT
ERROR OUT
STATUS OUT
The memory address and data structure of the record buffer is configured by the DATA
parameter of a DataLogCreate instruction. You must programmatically load the record buffer
with current run-time process values and then execute the DataLogWrite instruction to move
new record data from the buffer to the data log.
The ID parameter identifies a data log and data record configuration. The ID number is
generated when a data log is created.
If there are empty records in the circular data log file, then the next available empty record
will be written. If all records are full, then the oldest record will be overwritten.
CAUTION
Potential for data log data loss during a CPU power failure
If there is a power failure during an incomplete DataLogWrite operation, then the data
record being transferred to the data log could be lost.
Table 8- 133 Values of ERROR and STATUS
ERROR STATUS (W#16#)
0 0000
0 0001
0 7000
0 7001
0 7002
1 8070
1 8092
1 80B0
S7-1200 Programmable controller
System Manual, 11/2011, A5E02486680-05
Data type Description
Bool A low to high (positive edge) signal starts the operation. (Default value: False)
DWord Numeric data log identifier. Only used as an input for the DataLogWrite
instruction. (Default value: 0)
Note: Symbolic name access for this parameter is not allowed.
Bool The DONE bit is TRUE for one scan, after the last request was completed with
no error.
Bool
0 - No operation in progress

1 - Operation on progress

Bool The ERROR bit is TRUE for one scan, after the last request was terminated
with an error. The error code value at the STATUS parameter is valid only
during the single scan where ERROR = TRUE.
Word Execution condition code (Default value: 0)
Description
No error
Indicates that the data log is full: Each data log is created with a specified
maximum number of records. The last record of the maximum number has been
written. The next write operation will overwrite the oldest record.
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
th
All internal instance memory is in use.
Data log does not exist.
Data log file is not open (for explicit open mode only).
101BExtended instructions
8.7 Data logging
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