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1 FUNCTIONS
1.2 SLMP Communications
Communication structure
When a message is sent from the external device to the Ethernet-equipped module using the SLMP message format, the
Ethernet-equipped module executes a processing corresponding to the received message. During communication, the
Ethernet-equipped module functions as a server and the external device (terminals such as a personal computer) functions as
the client. The server (Ethernet-equipped module) automatically returns a response message suitable for the request
message received from the client.
Data communication procedures
This section describes the procedures for communicating with SLMP.
1. After the module parameters are set, the system checks that the initial processing of the Ethernet-equipped module has
ended normally. ('Initial status' (Un\G1900024.0): On)
2. Perform the open processing to establish a connection between the Ethernet-equipped module and external device.
( Page 378 TCP/IP Communications, UDP/IP Communications)
3. After the connection is established, the SLMP messages are sent from the external device.
4. Close the connection when communication is finished.
In the following case, the Ethernet-equipped module performs a remote password check when the external
device is accessing the programmable controller. If communication is not possible, unlock the remote
password. ( Page 177 Access permit processing (Unlock processing))
• When remote password is set for the CPU module.
• When connection for exchanging data with external device is set as a remote password check target.
(1) Server side: Ethernet-equipped module
(2) Client side: External device
(1)
(2)
Ethernet
Header Command
Access
destination
Request message
Subheader
Header Response dataSubheader
Response message
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