Mitsubishi Electric MELSEC-L Series - Communications Using a Random Access Buffer Cannot be Performed

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CHAPTER 16 TROUBLESHOOTING
16
16.6 Troubleshooting by Symptom 16.6.10 Communications using a random access buffer cannot be performed.
16.6.10 Communications using a random access buffer cannot be
performed.
The following table lists how to troubleshoot the problem when an E71 cannot perform communications using a
random access buffer.
If the action above does not solve the problem, perform the following tests on the E71 to check for hardware error.
• Hardware test ( Page 333, Appendix 6.2)
• Self-loopback test ( Page 332, Appendix 6.1)
Check item Action
Has the connection with the connected device been opened?
(Check the corresponding bit of 5000
H
in the buffer memory.)
• Open the connection with the connected device.
• Check if the open/close process for I/O signals and the OPEN/CLOSE
instructions are used together for the same connection. If so, correct the
program.
Did the connected device send a command? Send a command to the E71.
Was a response returned to the device that had sent the
command?
• Check if the correct IP address was specified in the command. If not,
correct the IP address and send the command again.
• Check if the communication protocol (TCP/IP or UDP/IP) matches with
that of the connected device. If not, correct it.
Is the end code of the response 0? Check the end and error codes to correct the error.
Is the correct buffer memory address specified for the
command?
Correct the buffer memory address and send the command again.
Has data been set in the specified address of the random
access buffer?
Write the data.
Has the write data been set in the connected device? Set the data.
Has an open or initial error occurred in the error log area? Check and correct the error.