Mitsubishi Electric Q03UDVCPU User Manual page 103

(3) Precautions
(a) Use of UDP
Data may be lost, or may arrive out of order.
Consider the application of TCP if any problem is expected.
(b) Sending and receiving data
Data sending process may be terminated even if the communication line between the CPU module and target
device is not connected due to a reason such as cable disconnection.
To avoid this, it is recommended to provide communication procedures at the user's discretion.
(c) Changing the target
Use the SP.SOCCSET instruction to change the target device.
For the SP.SOCCSET instruction, refer to:
(d) Open completion signal and Open request signal
Once UDP is selected for a connection, the Open completion signal and Open request signal of the connection
are always on.
(e) SP.SOCCLOSE instruction
Do not execute the SP.SOCCLOSE instruction in the program.
Doing so will disable data transfer since the Open completion signal and Open request signal of the
corresponding connection turn off for close processing.
To reopen the closed connection, execute the SP.SOCOPEN instruction.
For the SP.SOCOPEN instruction, refer to:
(f) Simultaneous broadcast targets
With simultaneous broadcast, data can be sent to the devices which are connected to the same hub of the
CPU module, and to those connected to the cascaded hub(s).
Data cannot be received from the devices connected through routers.
(g) Receiving data using simultaneous broadcast
When data are received through a connection of simultaneous broadcast, the IP address and port number of
the sender can be acquired by the SP.SOCCINF instruction.
For the SP.SOCCINF instruction, refer to:
(h) Connection of simultaneous broadcast
Data cannot be sent when FFFF
To send data, specify a value other than FFFF
Page 127, Section 7.4.7
Page 106, Section 7.4.1
Page 124, Section 7.4.6
is specified for the port number of the transmission target.
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