Mitsubishi Electric MELSEC iQ-R Series, Programming Manual

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1104
8 BUILT-IN ETHERNET FUNCTION INSTRUCTIONS
8.2 Socket Communications Instructions
■
Control data
*1 This item is invalid for UDP communications connections.
Processing details
• This instruction changes the TCP receive mode and receive data size for the connection (other than a UDP
communications connection) specified by (s1).
• For TCP connections, the function enables the mode specified by (s2)+2.
■
TCP standard receive mode
Upon receipt of data, the instruction stores the data in the socket communications receive data area and turns on SD1506
(socket communications receive status signal).
If the received data exceeds the specified receive data size, the excess data becomes the next receive data.
If data is received later before data is read from the socket communications receive data area using the SP.SOCRCV or
S.SOCRCVS instruction, it is stored in the receive data area in the OS.
If the receive data area in the OS contains data when data is read from the socket communications receive data area using
the SP.SOCRCV or S.SOCRCVS instruction, the instruction stores the data in the socket communications receive data area
and turns on SD1506 (socket communications receive status signal).
Ex.
When 500 bytes of data is received while the receive data size is set to 300 bytes
Operand: (s2)
Device Item Description Setting range Set by
+0 System area
  
+1 Completion status The completion status is stored upon completion of the instruction.
• 0000H: Completed successfully
• Other than 0000H: Completed with an error (error code)

System
+2 TCP receive mode
*1
Store the TCP receive mode.
• 0: TCP standard receive mode
• 1: TCP fixed-length receive mode
0, 1 User
+3 Receive data size Store the size of socket communications receive data (Number of bytes) 1 to 10238 User
OFF
ON
OFF
ON
OFF
Reading receive data
Storing data
(300 bytes)
Reading data
Storing data
(200 bytes)
Reading data
Socket communications
receive data storage area
Socket communications
reception status signal
(SD1506.n)
Receiving data
(500 bytes)
SP.SOCRCV or
S.SOCRCVS instruction
SP.SOCRCV or
S.SOCRCVS instruction