Mitsubishi Electric MELSEC-L Series - Data Cannot be Received with Communications Using a Fixed Buffer

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16.6.9 Data cannot be received with communications using a fixed
buffer.
The following table lists how to troubleshoot the problem when an E71 cannot receive data with communications using
a fixed 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
Does the receive data length match with the amount of data
actually received?
If the amount of the actually received data is smaller than the receive data
length, receive the remaining data. If it is larger than the receive data
length, receive the excess data as the next request message or discard it.
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 processes for I/O signals and the OPEN/CLOSE
instructions are not used together for the same connection. If so, correct
the program.
• Read Open error code (address: 7C
H
) in the communication status
storage area. Then check the error details and correct the error.
Is the IP address setting of the connected device correct? Check and correct the IP address of the connected device.
Does the communication protocol (TCP/IP or UDP/IP) match
with that of the connected device?
Use the same communication protocol (TCP/IP or UDP/IP) as that of the
connected device.
Is the receive status signal of the corresponding fixed buffer
on? (Check the corresponding bit of 5005
H
in the buffer
memory.)
Data was not sent from the connected device. Check the connected device
on the sending side and correct the error.
Was the BUFRCV instruction executed?
• Correct the execution conditions of the BUFRCV instruction.
• Check if the send/receive processes for I/O signals and the
BUFSND/BUFRCV instructions are not used together for the same
connection. If so, correct the program.
Was the BUFRCV instruction completed normally?
Check the error code in the BUFSND instruction completion status area
and correct the error.
Was the BUFRCVS instruction executed?
• Correct the interrupt setting of the programming tool.
• Check if the send/receive processes for I/O signals and the
BUFSND/BUFRCV instructions are not used for the same connection. If
so, correct the program.
Is the control data of the BUFRCVS instruction correct? Correct the control data.
Has an open or initial error occurred in the error log area? Check and correct the error.