Mitsubishi Electric MELSEC iQ-R-R00CPU User Manual page 140

■File size
The size for event history files can be changed in event history setting (Page 136 Event history setting). If the storage size
exceeds the specified size, records are deleted in order from the oldest one and the latest one is stored. An event history file
size is obtained from the following calculation formula.
Event history file size = File header size + Event history management information size + (Number of records  Size per event
history record)
Element
File header size
Event history management information size
Size per event history record
*1 Because the contents of detailed information may differ depending on the event to be saved or the detailed information may include a
variable-length file name, the size per event history record is variable.
The number of events to be saved in the event history file differs depending on the event type to be saved. When the event
history file size is 128K bytes (default), 1365 events can be registered if programs (whose program name is 8 characters (12
characters including a period and extension)) are written to the CPU module using the engineering tool.
[Calculation formula]
• 128 bytes  1024 = 131072 bytes
• 131072 bytes - (20 bytes + 12 bytes) = 131040 bytes
• 131040 bytes  96 bytes = 1365 events
Ex.
The table below shows the size of each element when 100 programs (whose program name is 8 characters (12 characters
including a period and extension)) are written to the CPU module by the following operating procedure.
Operating procedure
1.
Turn on the power in the STOP state.
2.
Write the system parameter, CPU parameter, module parameter, and 100 programs (whose program name is 8
characters (12 characters including a period and extension)) to the CPU module using the engineering tool.
3.
Switch the CPU module to the RUN state.
Element
File header
Event history management information
Event to be saved
Total
*1 The size will be 56 bytes for the process CPU with firmware version "06" or later.
6 RAS FUNCTIONS
138
6.4 Event History Function
Power-on and reset
Operating status change (STOP)
Writing files/folders (SYSTEM.PRM)
Writing files/folders (CPU.PRM)
Writing files/folders (UNIT.PRM)
Writing files/folders (MAIN_001.PRG to MAIN_100.PRG)
Operating status change (RUN)
Size
20 bytes
12 bytes
*1
40 bytes minimum
Size (byte)
20
12
*1
40
40
96
88
88
9600
40
10024