Missing Data; Conditions Under Which Missing Data Occurs; Errors Generated During Data Logging; Special Relay And Special Register Used By The Data Logging Function - Mitsubishi Electric FX5 User Manual

19.9

Missing Data

The term "missing data" means that some of the collected data is missing, resulting in data discontinuity.

Conditions under which missing data occurs

Missing data occurs under the following conditions:
Item
Processing overflow
Operations for the CPU module
Operation from engineering tools, CPU
Module Logging Configuration Tool, and
external devices via protocols such as SLMP
*1 The following operation also is included:
⋅ Online operation which displays data by operation such as read from the PLC performed from an engineering tool (retrieval and display
of a list of files on the CPU module)
⋅ View of the event history (retrieval of the event history from the CPU module)
Processing overflow
In normal cases when the usage of the internal buffer reaches the specified maximum capacity, the CPU module overwrites
the data stored in the storage memory on a first-in first-out basis. If the internal buffer becomes full before all of the data stored
in it is saved to the storage memory, however, the CPU module does not overwrite the existing data and stops storing data in
the internal buffer, thus resulting in missing data. This situation is referred to as processing overflow. Upon the occurrence
overflow, the special register (Number of processing overflow occurrences) stores the number of times when processing
overflow occurred.
19.10

Errors Generated During Data Logging

No diagnostic error occurs if an error occurs during data logging, the SM applicable to the special relay (data logging error)
setting No. turns on, and the error cause is stored in the SD applicable to the special register (data logging error cause)
setting No. Note that if the data logging with the special relay fails at the time of register/clear, the cause of occurred error is
stored in a special register (the data logging register/clear error code) applicable to the setting No.
19.11
Special Relay and Special Register Used by the
Data Logging Function
For details on the special relays and special registers used by the data logging function, refer to the following:
• Special relay: Special relay related with the data logging function (Page 323 Data logging function)
• Special register: Special register related with the data logging function (Page 356 Data logging function)
19 DATA LOGGING FUNCTION
140
19.9 Missing Data
Description
• When the internal buffer responsible for tentatively storing the logged data is unable to store new logged
data because the SD memory card does not store data
• When you attempt to register the data logging while the CPU module is in the process of logging collecting,
collecting before trigger or collecting after trigger
The CPU module has been stopped and run with "Operation at transition to RUN" set to "Auto Start."
The CPU module has been turned off and on with "Operation at transition to RUN" set to "Auto Start."
The CPU module has been reset and run with "Operation at transition to RUN" set to "Auto Start."
• When the CPU module is suspended and restarted, and operation for displaying the logging state is
performed from CPU Module Logging Configuration Tool
*1
• File read , write, delete, or verification