Specifications

2 - 21
Open status
Open ready status
(closed)
Closed status
Initial normal completion X19
OPEN instruction
OPEN instruction complete device
OPEN instruction complete device +1
Open error detection signal X18
CLOSE instruction
CLOSE instruction complete device
CLOSE instruction complete device +1
Open completion signal
(Address: 5000
H
)
Open request signal
(Address: 5002
H
)
Power-on
One scan
3) 4)
5)
2)
1)
Parameter
communication
completed
One scan
(Active open acceptable)
SYN+ACK FIN+ACK
FIN
SYN
(*2)
(*1)
Number Description
1)
After the parameter communication, confirm normal completion of the Ethernet module initial processing.
(Initial normal completion signal (X19): ON)
2)
Start the open processing using the dedicated instruction, OPEN.
(Open request signal (address: 5002
H … b0): ON)
3)
The Ethernet module starts the open processing upon receiving the open request (SYN) from the external device.
• When the open processing completes normally
The open completion signal (address: 5000H… b0) turns on and data communication is enabled.
• When the open processing completes abnormally
Confirm "Complete status" stored in the control data of the OPEN instruction and perform the recovery processing.
4)
The Ethernet module starts the close processing upon receiving the close request (FIN) from the external device.
When the close processing is completed, the open completion signal turns off and the data communication is disabled.
5) Start the close processing using the dedicated instruction, CLOSE. (Open request signal: OFF)
*1 An open request (SYN) received during the time from normal completion of
the initial processing to change to the open acceptable status generates an
error, and the Ethernet module sends a connection forced close (RST).
*2 The above chart shows how the Ethernet module side closes a connection in
response to a close request from the external device side.
When disconnecting the connection from the Ethernet module side, the
CLOSE instruction is executed using the sequence program to start the close
processing.
(The FIN is sent and the FIN+ACK is received.)