Mitsubishi Electric MELSEC iQ-R Series User Manual page 462

Internal buffer
The internal buffer which is used to temporarily store collected data frees up the memory capacity up to the capacity assigned
to the logging function by "System memory setting". Adjust the system memory setting according to the number of logging
settings and data.
The following shows a rough standard of the required amount of memory for logging.
Minimum required amount per setting (kB) = 100 + (The total number of the appropriative words for each data) × R × B
Item
Minimum required amount per setting
Item
Total number of the appropriative
words for each data
R: Number of records
B: Number of buffer
SD memory card replacement [RD78G(H)]
When the storage location of the data logging files is set to an SD memory card, the SD memory card can be replaced by
using the SD memory card forced disable function even while data logging is in progress. Only the data saving to the SD
memory card is stopped. The data collection keeps working.
Precautions
If a new SD memory card is inserted before the next file saving is started, the logging result is saved to the new SD memory
card. If a SD memory card is not inserted before the next file saving is started, the file saving is failure and an error occurs.
15 LOGGING
460
15.1 Data Logging/Real-Time Monitor
Description
It may increase more than the minimum required amount depending on the setting order of the data when different
types of word data exist as the target data. For the internal buffer, the number of appropriative words of the smaller
type may be rounded up to the number of the appropriative words of the next bigger type. Because the two-word data
and the four-word data are set in the two-word border and the four-word border respectively.
(Ex.)
When setting the order of four-word data, one-word data, four word data, the number of the appropriative words is 12.
(The number of the appropriative words for one word data is rounded up to 4.)
Description
The number of the appropriative words per one for each data is shown below.
Bit: 1 / 16 (one word for 16)
Word (signed): 1
Double word (signed): 2
Word (unsigned): 1
Double word (unsigned): 2
Single-precision real number: 2
Double-precision real number: 4
During continuous logging: R = Number of file switching records (SAVSWICTMNRECNUM)
In trigger logging: R = Number of trigger records before trigger (LLNBEFOR) + Number of trigger records after trigger
(LLNAFTER)
When the specification of the number of buffer (NUMBUFF) is 2 to 10: B = NUMBUFF
When the specification of the number of buffer (NUMBUFF) is 0, and when the number of records R × collection
interval is within 1 [s]: B = 4
When within 1 [s] to 5 [s]: B = 3
Other than the above: B = 2