ESIGN PRECAUTIONS]
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DANGER
If a communication error occurs in the network, the error station (MELSEC-ST system) shows
the following behavior.All outputs turn OFF. (In the MELSEC-ST system, the output status at
the time of error can be set to clear/hold/preset by using user parameters of each slice module.
As “clear” is set by default, the outputs turn OFF when an error occurs. In the case where the
system operates safely with the output set to “hold” or “preset”, change the parameter
settings.)Create in the program an interlock circuit that will ensure the system operates safely
based on the communication status information.Failure to do so may cause an accident due to
mis-output or malfunction.

Create an external fail safe circuit that will ensure the MELSEC-ST system operates safely,
even when the external power supply or the system fails.
Accident may occur due to output error or malfunctioning.
(1) The status of output changes depending on the setting of various functions that control the
output. Take sufficient caution when setting for those functions.
(2) Normal output may not be obtained due to malfunctions of output elements or the internal
circuits.Configure a circuit to monitor signals which may lead to a serious