7.2.2 Close Connection - Hitachi EH-150 Applications Manual

7.2.2 Close connection

The procedure for closing connection is shown as Figure 7.9.
Host PC
(A-2)
(A-3)
(A) In case EH-ETH2 requests to close connection
(A) In case EH-ETH2 requests to close connection
(A-1) EH-ETH2 requests to close connection to the host PC.
Host PC receives the request to close from EH-ETH2 , and
(A-2)
replies back ACK.
When the host PC does not have data to send, it replies back
(A-3)
FIN ACK.
EH-ETH2 receives the FIN ACK and close after waiting a
(A-4)
time designated in Time wait value.
(B) In case Host PC requests to close connection.
(B-1) Host PC requests to close connection to the EH-ETH2.
EH-ETH2 receives the request to close from Host PC, and
(B-2)
replies back ACK
When the EH-ETH2 does not have data to send, it replies
(B-3)
(*1)
back FIN ACK.
(B-4) The host PC receives the FIN ACK and replied back ACK.
*1: This is only in case "Close mode control" is disabled. The "Close mode control" is mentioned in the
followings.
Figure 7.9
Caution
- In case of the task code communication connection, a host computer must send a request to close.
Chapter 7 Automatic Sending/Receiving function (ASR)
EH-ETH2
(A-1)
(A-4)
Description
Description
Basic procedure to open connection
7-10
Host PC
(B-1)
(B-4)
(B) In case host PC requests to close connection
Segment
Sending FIN flag
Sending ACK flag
Sending FIN ACK flag
Sending ACK flag
Segment
Sending FIN flag
Sending ACK flag
Sending FIN ACK flag
Sending ACK flag
EH-ETH2
(B-2)
(B-3)
EH-ETH2
internal status
Connection opened
(ESTABLISHED )
Waiting for a request
to close1
(FIN WAIT-1 )
Waiting for a request
to close2
(FIN WAIT-2 )
Waiting
(TIME WAIT ),
connection closed
(CLOSED )
EH-ETH2
internal status
Connection opened
(ESTABLISHED )
Waiting for closing
(CLOSE WAIT )
Waiting for a final
response
(LAST-ACK)
Connection closed
(CLOSED )