Appendix 15Sd Memory Card Life - Mitsubishi Electric MELSEC iQ-R Series User Manual

Appendix 15
An SD memory card has a life (a limit on the number of times for writing data). The following shows the method for calculating
the life of an SD memory card.
Note that the actual life depends on the operating conditions and environment. Use the following calculation as a guide to
determine the time for replacement.
Calculation formula of SD memory card life
SD memory card life (year) = Total size of writable data (GB)  Size of data written per year (GB/year)
Total writable size
Capacity  Number of writes
*1 For the capacity of applicable SD memory cards and the number of writes, refer to the following:
MELSEC iQ-R Module Configuration Manual
Size of data written per year
The size of data written per year is obtained by the following formula:
Size of data written per year (GB/year) = (DS1
*1
+ 6144)  DCNn + (ES1
+ (DCSn
+ 6144)  ECNn + (RS1  RN1 + ... + RSn  RNn)  1073741824
*1 Round up DSn, DCSn, ESn and ECSn to a multiple of 512.
DSn, DNn, DCSn, DCNn, ESn, ENn, ECSn, ECNn, RSn, and RNn are obtained as follows.
■One record size for data logging (DSn)
Unicode text file format and CSV file output format: Refer to the data line. (Page 355 Unicode text file/CSV file)
Binary output format: Refer to the data. (Page 361 Binary file)
■Number of records written for data logging per year (DNn)
Continuous logging: DNn = 60  60  24  365  Collection interval and timing (seconds)
Trigger logging: DNn = Total number of records
*1 The value that is determined depending on the condition set in "Sampling" when "Continuous logging" is selected for the logging type.
(When the value is determined in milliseconds, convert the value into seconds. When each scan is specified, check the scan time of the
control CPU.)
*2 Calculate the rate using the system operating time. For example, if the operating time per year is 5000 hours, the operating rate is
calculated as follows: 5000  (24  365) = 0.57.
*3 The value set when "Trigger logging" is selected for the logging type.
*4 This value is calculated by the anticipated count according to system operation.
■Header size for data logging (DCSn)
Unicode text file format and CSV file output format: Refer to the file information line to data name line. (Page 355 Unicode
text file/CSV file)
Binary output format: Refer to the header. (Page 361 Binary file)
■Number of file switches for data logging per year (DCNn)
Calculate the number by the anticipated count according to the file switching setting and system operation. For example,
when 1000 records are set in "Number of records" of "File switching timing" in the [File] tab and "Each scanning cycle" is
specified for "Sampling interval" in the [Sampling] tab, the time interval of the file switching is obtained by multiplying the scan
time by 1000. Therefore, the number of file switching times for the data logging per year is obtained by the following formula:
60  60  24  365  (Scan time (second)  1000)
APPX
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Appendix 15 SD Memory Card Life
SD Memory Card Life
*1
*1
+ 6144)  DN1 + ... + (DSn
*1
+ 6144)  EN1 + ... + (ESn
*3
 trigger occurrence count for 1 year
*1
+ 6144)  DNn + (DCS1
*1
+ 6144)  ENn + (ECS1
*1
*4
*1
+ 6144)  DCN1 + ...
*1
+ 6144)  ECN1 + ... + (ECSn
*2
 Operating rate
*1