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27 TROUBLESHOOTING
27.3 Troubleshooting by Symptom
ERR LED turns ON
Symptom Cause Corrective action MC Non Bi Pd
ERR LED turns ON. The online mode switching
designation is incorrect.
• Read the error code from the buffer memory, and check the
error contents and correct the designation contents.
The receive data clear
request is executed during the
dedicated instruction
execution.
• Read the execution result (error code) of control data for the
dedicated instruction of which the abnormal completion
signal has turned ON, and take the corrective action
corresponding the error contents.
The power of C24 was turned
OFF while writing to the flash
ROM.
• Write the data again to the flash ROM.
An error is detected. • Check if any symptom corresponding to the troubleshooting
by symptom occurs, and remove the cause of the error.
(Page 457 Troubleshooting by Symptom)
When the predefined
protocol is executed, the
ERR LED turns ON.
The communication protocol
setting is set to other than
"Predefined protocol".
• Set the communication protocol setting to "Predefined
protocol".
No protocol setting data has
been written.
• Write the protocol setting data with the Predefined protocol
support function of Engineering tool, and then execute the
CPRTCL instruction.
The protocol corresponding to
the protocol number specified
in the control data for the
CPRTCL instruction is not
registered.
• Read the protocol setting from C24 with the Predefined
protocol support function of Engineering tool.
• On the "Add Protocol" screen, check for the registered
protocol and protocol No., and correct them if incorrect.
Multiple CPRTCL instructions
were simultaneously
executed to the same
channel.
• Review the program so that the next CPRTCL instruction is
executed once one CPRTCL instruction execution is
completed.
Incorrect control data are
specified for the CPRTCL
instruction.
• Review the control data for the CPRTCL instruction.
The edited protocol setting
with the Predefined protocol
support function of
Engineering tool is
inconsistent with the packet
format of the target device.
Check the packet format of the target device, and review the
protocol setting taking the following into consideration.
• When a Conversion variable exists in the received packet,
are conversion contents or the settings for sign character,
number of decimals, or number of digits incorrect?
• When a check code exists in the received packet, are the
processing method or the settings for code type, data
length, data flow, complement calculation, or calculating
range incorrect.
• When a Length exists in the received packet and a
Conversion variable is included in the calculating range of
the Length, are the code type or the settings for data length,
data flow, or calculating range incorrect?
An expected packet has not
been received, and the
monitoring timeout error
occurred.
• Check the data transmitted from the target device with the
Circuit Trace function of Engineering tool, and correct it if the
message is in correct.
Communication error
occurred.
• Check the error description with the System Monitor
function, and remove the cause of the error.
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