Mitsubishi L02CPU User Manual page 78

(d) Precaution for Passive open communication
• Configure an interlock circuit using the Open completion signal (SD1282) and Open request signal
(SD1284) in the program. The following chart shows on/off timings of the Open completion signal and
Open request signal.
Open completion signal
(SD1282)
Open request signal
(SD1284)
• When a device establishes a connection by Passive open, the IP address and port number of the connected
device can be acquired using the SP.SOCCINF instruction. For the SP.SOCCINF instruction, refer to Page
106, Section 7.4.6.
• On TCP, one connection is established with one target device. To communicate with multiple devices from
one port number, prepare the same number of connections as that of the target devices. A connection that
exceeds the preset number of connections will be disconnected immediately.
• Do not accept a connection from a device until the CPU module is placed in the wait-for-open state. If a TCP
connection request is received before entering the wait-for-open state after completion of CPU startup, the
request will be recognized as an error, and a forced close message for the connection will be returned to the
interfacing device. In this case, wait until the CPU state is changed to the wait-for-open state and then retry
the connection from the device.
• Do not execute the SP.SOCCLOSE instruction in a 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 a closed connection, execute the SP.SOCOPEN instruction. For the SP.SOCOPEN
instruction, refer to Page 86, Section 7.4.1.
76
ON
OFF
ON
OFF
TCP connection completed
by the external device
TCP disconnection completed
by the external device
Always on