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8. If Transmission Using TCP Sockets Fails

When troubleshooting TCP sockets, also refer to the section "TCP socket interface notes" in

section 6.2, Ethernet Port Socket Interface Usage Notes.

a. Open request

START
Resolve the problem by referring
to the status.
Decide which role each socket will play when
establishing a connection between a pair of
sockets.
Verify the status using the
procedure described in the
item 3 " If a SEND or RECV
instruction fails complete"
on page 148.
No
Did the SEND instruction
complete?
Yes
No
Was the wait time set to
unlimited?
Yes
Set the Ethernet Port to run
+ socket transmission
enabled using an operating
mode control request.
No
¬
¬
Did the instruction time out?
TermSTS = 0BH
Details = 0020H
Yes
No
Is the station status such that
run + socket transmission is
enabled?
Yes
No
Is the program attempting to
issue an active open to a
socket in the passive open
state?
Yes
Verify the remote port IP address and TCP port
number.
No
Are the remote port IP
address and TCP port
number correct?
Yes
1.Recheck the remote port IP address and
message transmission TCP port numbers.
2.Verify that there is no router on the network.
3.Check the network verification items.
No
Does a response come back
if a ping is issued to the
remote port?
Yes
RAS error counters: Alignment error
Short packet
CRC error
It is possible that there is an abnormality on the
network itself. Check the network verification
items.
No
Is the error counter read out
from the RAS information
constant (i.e., not being
incremented)?
(Use RAS information
readout to determine this.)
END
Yes