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If the timeout time expires, the "transmission complete timeout (no instruction response)"
error is issued. Since this error has the same code as module failure errors, first check whether
or not the Ethernet Port has failed before attempting to recover from the error.
h. User programs specify the time limit until completion for the following three requests used in
socket interface transmission:
• UDP receive request
• TCP open request
• TCP receive request
If this time limit is exceeded, a "timeout" error is issued. In particular, the Ethernet Port
reports the timeout error to the T2N.
i. The Ethernet Port uses a priority ordering in processing sockets 1 through 8. Therefore,
systems constructed so that socket 1 is activated frequently may not be able to process socket
8, resulting in "Transmission completion timeout" errors occurring. When constructing a
system, take the socket utilization conditions into account when allocating sockets.
Since the send/receive processing for each socket requires about 50 ms, applications that issue
send or receive requests to a given socket should leave an interval of at least 50 ms times the
number of sockets used between each request.
(Interval between requests to the same socket) ≥ (Number of sockets used × 50 ms)
Similarly, the above intervals averaging 50 ms should be left between transmissions from
remote ports to the local port.
(Interval between remote port transmissions) ≥ (Number of remote ports × 50 ms)
5. UDP socket interface notes
a. In transmission using UDP sockets, the user program must implement any processing required
to assure transmission reliability, such as verifying the reception of transmitted data and
retransmission.
b. It is possible to broadcast to all ports on the network using UDP sockets.
Send side: Set the transmission destination address to "255.255.255.255". This is
"FF.FF.FF.FF" in hexadecimal. The "0.0.0.0" used by some UNIX
versions (in particular, 4.2 BSD) cannot be used.
Set the UDP port number for the socket to which you want to issue a
broadcast as the transmission destination object socket UDP port
number. It is convenient to prepare a dedicated socket in advance if
broadcast transmission is to be used.
Receive side: Specify "0.0.0.0" as the transmission source IP address.
Specify the UDP port number for the broadcast transmitting socket as the
transmission source UDP port number.
c. Data transmission between sockets on the same port is not supported by UDP.
d. When PC link transmission or the UDP socket interface is used, if an application
transmits to a nonexistent remote port, an transmission error (TermSTS = 0BH, detailed
information = 0020H) occurs.