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8 BUILT-IN ETHERNET FUNCTION INSTRUCTIONS
8.2 Socket Communications Instructions
• The SP.SOCRCV instruction reads the receive data of the connection specified by (s1) from the socket communications
receive data area (where the data received from an external device in each connection is stored) by the END processing
after the instruction execution.
• The execution status and the completion status of the SP.SOCRCV instruction can be checked with the completion device
(d2) and the completion status indication device (d2)+1.
• The following figure shows the execution timing of the SP.SOCRCV instruction.
When reading receive data from the same connection, do not use this command together with the S.SOCRCVS instruction.
Upon completion with an error, the completion status indication device (d2)+1 is turned on and an error code is stored in the
completion status (s2)+1.
For the error code stored in the completion status (s2)+1, refer to the following.
MELSEC iQ-R Ethernet User's Manual (Application)
• To avoid receiving too much amount of data, the SP.SOCRMODE instruction can be used to set the size of
receive data to limit the amount of receive data.
• By connecting the completion device of the SP.SOCRCV instruction to the execution instruction through a
normally closed contact, data can be read continuously even when it is received continuously.
• Completion device (d2)
This device turns on during END processing of the scan where the SP.SOCRCV instruction completes, and turns off during the next END processing.
• Completion status indication device (d2)+1
This device turns on or off depending on the completion status of the SP.SOCRCV instruction.
When completed successfully: The device remains off.
When completed with an error: The device turns on during END processing of the scan where the SP.SOCRCV instruction completes, and turns off during the
next END processing.
Error code
(SD0)
Description
2820H The amount of data received exceeds the relevant setting area in the device/label memory in the receive data storage device.
3405H The connection number specified by (s1) is a value other than 1 to 16.
··
(d1)+0
(d1)+1
(d1)+2
(d1)+n
CPU module
Receive data length
SP.SOCRCV
(reading
receive data)
Socket communications
receive data storage area
Connection number
specified by (s1)
Receive data
Receive data
Receive data
External device
Receiving
data
END0 END0END0END0
OFF
OFF
OFF
OFF
ON
ON
Sequence scan
SP.SOCRCV
instruction
Completion device (d2)
Completion status
indication device (d2)+1
Completed successfully
1 scan
Reading data
Execution of the instruction
Receiving data
Completed with an error
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