Logging Of The Event History - Mitsubishi Electric MELSEC iQ-R Series User Manual

Logging of the event history

This section describes events saving for the event history.
Event history file
The storage memory and file size for event history files can be changed in event history setting. ( Page 212 Event history
setting)
■Storage memory
Choose either the data memory or SD memory card.
If the storage memory is the SD memory card: when the write protect switch of the SD memory card is enabled, an event
history will not be stored. (It is possible to read the event history file in SD memory card using the engineering tool.) Therefore,
if the write protect switch of the SD memory card is changed into "Disabled  Enabled" during operation, the write error to the
SD memory card occurs when the event for storing into event history is generated (SD memory card available event is
registered) after the write protect switch is enabled. An error that has occurred can be checked by using the module
diagnostics of the engineering tool immediately after its occurrence. However, these errors are not stored in the event history
after powering off and on or reset of the CPU module.
■File size
The size for event history files can be changed in event history setting ( Page 212 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
Size
20 bytes
12 bytes
*1
40 bytes minimum
Size (byte)
20
12
15 RAS FUNCTIONS
15.4 Event History Function
15
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