19 DATA LOGGING FUNCTION
19.6 Precautions
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19
19.6 Precautions
This section describes precautions to take when using the data logging function.
Missing data
The term "missing data" means that some of the collected data is missing, resulting in data discontinuity.
Missing data occurs under the following conditions:
*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)
■Data logging function processing time
The data logging function processing time indicates the minimum time value that allows data collection without data loss when
executing data logging.
It shows the collection interval at which data can be collected under the following conditions.
• Logging type = continuous logging
• Scan time = 5ms
• Internal buffer capacity setting = 80K bytes as per one setting (default setting)
• Collection setting = Time specification (data collection at time interval)
• Data setting = Data register (D) (Data type: Word (signed))
• Binary Output setting = Output date (output format is default), Output data sampling interval, Output index, Output
comments
• Save setting = Operation when exceeds the number of files: Overwriting, File switch timing: 10000
• SD memory card: NZ1MEM-4GBSD used
• If the SD memory card is accessed frequently during operations with the engineering tool or CPU module logging setting
tool or with operations using FTP, set a longer collection interval than the interval given above.
• If a load on Ethernet communication is heavy for such a reason as using socket communication and SLMP communication,
set a longer collection interval than the interval given above.
Item Description
Data logging function processing time When data logging is executed by specifying for the collection interval a time interval shorter than the
processing time required by the CPU module for data storage.
Processing overflow • 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
Operations for the CPU module 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".
Operation from engineering tools, CPU
Module Logging Configuration Tool, and
external devices via protocols such as SLMP
• When the CPU module is suspended and restarted, and operation for displaying the logging state is
performed from CPU Module Logging Configuration Tool
• File read
*1
, write, delete, or verification
Points Collection interval where data can be collected
8 points (8 points 1 setting) 10ms
16 points (16 points 1 setting) 15ms
64 points (64 points 1 setting) 45ms
128 points (128 points 1 setting) 100ms
256 points (128 points 2 setting) 150ms
512 points (128 points 4 setting) 250ms
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