Omron SYSMAC CS1W-ETN21 Operation Manual page 244

Troubleshooting Procedures
Opening Problems
Opening Problems occurred.
N
Are you attempting
an active open?
Y
Is the passive open
not finishing?
N
Is the response
code in the results storage
area a value other
than 0049?
Y
Return to General
Problems.
Closing Problems
Use an active open at the
Y
remote node.
Read socket status using
N
the FINS command READ
SOCKET STATUS.
Does the port
number being used exist
at the local node?
N
Refer to General Problems on page 218.
Make sure that the same port number is not being used
simultaneously by more than one process, including FTP services.
Y
Sockets can remain in ESTABLISHED or some later status even if
closed; be sure to close ports from both sides of the connection.
A socket can remain open in TIME WAIT status for up to one minute
on the side that closes the socket first; we recommend that the
active-side port number be set to 0 and that you close the socket
from the active side. If you are using the Socket Service Request
Switches, check the response code to see if it is 0049 Hex.
Section 8-4
219