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8. TROUBLESHOOTING
Symptom
No Communication With A
Certain Station
Cannot Read Message
Communication
Cannot Write Message
Communication
Cannot Read Message
Communication Errors
A Communication Error
Occurs when DeviceNet is
Started Up
Check Item
Is the correct I/O data area referred to in buffer memory?
Check that the I/O data area is correct, referring to 3.4.2
Details of the Buffer Memory.
Is the correct baud rate set for the slave station?
Is a termination resistance correctly connected to each end
of the network?
Does the cable length exceed the permitted limit?
Check the cable length restrictions appropriate for the cable
thickness and baud rate, referring to 3.2 Performance
Specifications.
Check the parameter settings.
Check the error codes.
See 8.3 Troubleshooting using Error Codes.
Is Get Attribute (0101
) stored in the message
H
communication command area of buffer memory?
Also, are the correct station number of the slave station,
class ID, instance ID, and attribute ID stored in the message
communication command area of buffer memory?
Is message communication write processing or message
communication error read processing conducted at the
same time as the message communication read program is
executed?
Is Set Attribute (0102
) stored in the message
H
communication command area of buffer memory?
Also, are the correct station number of the slave station,
class ID, instance ID, and attribute ID stored in the message
communication command area of buffer memory?
Is message communication read processing or message
communication error read processing conducted at the
same time as the message communication write program is
executed?
Is Read Communication Error Information (0001
the message communication command area of buffer
memory? Also, is the correct station number of the slave
station stored in the message communication command
area?
Is message communication read processing or message
communication write processing conducted at the same
time as the message communication error read program is
executed?
Are parameters set by the configuration software and
parameters set by the sequence program both valid?
) stored in
H
−
8
4
MELSEC-A
Remedy
Set the correct reference area.
Make the baud rate setting match the
baud rate setting at the slave station.
Check if termination resistances are
connected and if they are connected
correctly.
Reduce the cable length.
Reduce the baud rate.
If thin cable is used in the trunk line,
replace it with thick cable.
See 8.1.2 Problems Due to Incorrect
Parameter Settings
Take the remedy described for the error
code.
Modify the sequence program to store
the correct values.
Modify the sequence program so that
these are executed at different times.
Modify the sequence program to store
the correct values.
Modify the sequence program so that
these are executed at different times.
Modify the sequence program to store
the correct values.
Modify the sequence program so that
these are executed at different times.
Disable one set of parameters, referring
to 6.2 Setting with a Sequence Program.
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Table of Contents
Troubleshooting
