Incomplete Data Reception And Timeout; Execution Interval Setting; Duplication Of Own Station Port Numbers; Device In The Communication Destination - Mitsubishi Electric MELSEC iQ-RJ71EN71 User Manual

Precautions

This section provides precautions for the simple CPU communication function.

Incomplete data reception and timeout

Because the load of Ethernet communication becomes heavy during the simple CPU communication, if the other
communication (MELSOFT connection or SLMP) is simultaneously performed by using UDP, the data reception of UDP may
not be completed, resulting in a timeout error. Therefore, to perform other communications during the simple CPU
communication, the communication using TCP is recommended.

Execution interval setting

The execution interval of the simple CPU communication function will differ according to the Ethernet line's load rate,
operating status of other communications (such as MELSOFT connection, SLMP communication, socket communication
function, CC-Link IE Field Network Basic), scan time of the communication destination, and system configuration. Thus, the
set execution interval or time required for completing the communications may be increased.
To perform communications at the set execution interval, set a sufficient execution interval. If checking the execution interval
is required, perform actual communications and check it with the "Simple PLC Communication Diagnostics" window.

Duplication of own station port numbers

The simple CPU communication cannot be performed in the following cases.
• The own station port number set in the simple CPU communication and the own station port number of the CPU module set
in the external device configuration are the same.
• The own station port number set in the simple CPU communication and the one set in another function such as the socket
communication are the same.
Set different own station port numbers. For the setting numbers other than the one in which a communication error occurs,
communications are performed after the preparation processing is completed normally.
IP address and module type of the external device
Check the IP address and module type of the communication destination device before setting the parameters. The simple
CPU communication cannot be performed when the communication destination does not exist (an incorrect IP address is
specified) or when the preparation processing is not completed.

Device in the communication destination

Check the type or range of the device to be read or written in the communication destination.
Especially, when "Write" is set for the communication pattern, since the control data of the communication destination may be
overwritten, communications may result in malfunction.
Remote password
The simple CPU communication cannot be performed when a remote password is set for the CPU module which performs the
simple CPU communication. Disable the remote password setting of the communication destination.
When using the file register (R, ZR)
When using the file register (R, ZR) for the device on the own station, always assign the device within the setting range. The
simple CPU communication of the setting number which exceeds the setting range due to a stop error of the own station
cannot be performed.
When a stop error occurs, communications of the setting number other than the one which exceeds the setting range continue
operating.
When using the special relay (SM) and special register (SD)
Do not write any data to the special relay (SM) and the special register (SD) that are set on the system side. Doing so may
cause a system failure or communication failure.
1.14 Simple CPU Communication Function (CPU Module (Built-in Ethernet Port Part))
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