Precautions - Mitsubishi L02CPU User Manual

(3) Operations after the error
After the occurrence of the error, if the conditions are restored for proper communications, data communications
are re-started at the following timing.
• When "Fixed" is set for Communication Setting: At the timing of the execution interval
• When "On Request" is set for Communication Setting: At the rising (off to on) of Request Contact
12.5

Precautions

This section provides precautions for the simple PLC communication function.
(1) The timing when the settings are enabled
The settings for this function are enabled at the following timing.
• When powering off and on the CPU module
• When resetting the CPU module
Even if the values of the settings are changed and the CPU module state is changed from STOP to RUN during
execution of this function, the CPU module keeps operating with the previous settings. Note that if the "Device"
setting of PLC parameter is changed and the parameters are written to the CPU module, an error (error code:
4900 ) occurs while the parameters are being written.
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(2) Communications with other CPU modules
The communications are possible only between the CPU modules connected over Ethernet. (Communications
with the other CPU modules cannot be performed through the CPU module connected over Ethernet.)
(3) Device data
If the COM instruction is used, not only the data in the END processing but also the data during sequence scan
(at the execution of the COM instruction) are subjected to communications. Therefore, if you want to use exact
data in the END processing for the program, conduct following operations.
[Transmission source] For the program, use a different device from the one specified for this function. At the end
of the program (just before the END), reflect the data of that device to the one specified for this function.
[Transmission destination] At the beginning of the program, reflect the data of the device specified for this
function to the other device, and use that device for the program.
(4) Incomplete data reception and timeout
Because the load of Ethernet communication becomes heavy during the simple PLC communication, if the other
communication (MELSOFT connection or MC protocol) is simultaneously performed by using protocol UDP, the
data reception of UDP may not be completed, resulting in a timeout error. Therefore, to perform other
communications during the simple PLC communication, the communication using TCP is recommended. Also
conduct following operations to reduce Ethernet communication load.
• Increase the execution interval of the simple PLC communication.
• Reduce the number of device points for communication.
(5) Communication stop
For a certain setting No., if the device is waiting for the response of the destination device due to power off of the
module, cable disconnection, or power off of the hub, communications for the other setting No. might be stopped
for 1000ms.
CHAPTER 12 SIMPLE PLC COMMUNICATION FUNCTION
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