Troubleshooting On The Entire System During Operation Of The Data Logging Function - Mitsubishi Electric MELSEC-L Series User Manual

13.2.3
Troubleshooting on the entire system during operation of the
data logging function
The following are examples of the system problems that may occur during operation of the data logging function and
corrective actions.
Symptom
It takes time to complete an access
(read or write) to the SD memory
card when the CPU module performs
the data logging function.
When the drive enabled by a
parameter is SD memory card, it
takes time to start the data link of
CC-Link.
A timeout error occurs when a
transmission or dedicated instruction
is sent from a peripheral device to
the CPU module in operation of the
data logging function.
It takes time to switch the operating
status of the CPU module.
Cause
Accesses are concentrated to the
SD memory card.
From the configuration tool,
multiple data loggings were
attempted to be started at the
same time
Multiple data logging settings have
been registered.
Data in the buffer are being saved
to the SD memory card.
Multiple data logging settings have
been registered.
Action
If the data logging is executed with the "short sampling interval" or "many
sampling data" setting, access to the SD memory card will occur frequently. In
that condition, accessing the SD memory card from another function will cause
concentration of accesses to the SD memory card, resulting in slow completion.
The following settings can reduce frequency of SD memory card access.
• Increase the sampling interval. (
• Decrease the number of sampled data. (
• Decrease frequency of file switching. (
If the data logging is executed with the "short sampling interval" or "many
sampling data" setting, access to the SD memory card will occur frequently.
When the parameter-enabled drive is SD memory card, if frequency of access to
the SD memory card in data logging is high, it takes time to read network
parameters from the SD memory card and thus to start the data link.
The following actions can shorten the time required for starting the data link of
CC-Link.
• Store the parameters in the program memory or standard ROM.
• Reduce frequency of SD memory card access by the following setting.
• EIncrease the sampling interval. (
• Decrease the number of sampled data. (
• Decrease frequency of file switching. (
Starting multiple data loggings will temporarily increase the load on the service
processing. This may slow down the communication response, causing a timeout
error. By modifying the service processing setting in PLC Parameter, occurrence
of a timeout error can be avoided. For the service processing setting, refer to the
following.
MELSEC-L CPU Module User's Manual (Function Explanation, Program
Fundamentals)
Occurrence of a timeout error can be also avoided by starting data loggings in
one setting after another
Since data logging settings are registered when the status changes from STOP
to RUN, processing time for the status change may be increased temporarily and
this may cause a timeout error.
• Increase a timeout time value of the external device
• Decrease the number of data logging settings.
The operating status of the CPU module does not change while data in the buffer
are being saved to an SD memory card by a specific operation (such as changing
the status from RUN to STOP and a stop or pause operation from the
configuration tool). ( Page 138, Section 9.1 (2))
• Wait until the data saving is complete.
Data logging settings are registered when the status changes from STOP to
RUN. The operating status of the CPU module does not change during
registration, regardless of the operation.
• Wait until the registration is complete.
• Decrease the number of data logging settings.
CHAPTER 13 TROUBLESHOOTING
Page 99, Section 8.4.4)
Page 101, Section 8.4.5)
Page 109, Section 8.4.10)
Page 99, Section 8.4.4)
Page 101, Section 8.4.5)
Page 109, Section 8.4.10)
(To the next page)
153
13