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[Design Precautions]
[Design Precautions]
WARNING
● In the case of a communication failure in the network, the status of the error station will be as follows:
Check the communication status information and configure an interlock circuit in the sequence
program to ensure that the entire system will operate safely. Failure to do so may result in an accident
due to an incorrect output or malfunction.
(1) The remote master station will hold the data before the communication error.
(2) The remote I/O station turns off all outputs. The output module of the remote I/O station can
clear/hold the output status at an error by using the remote I/O module parameters. As the
parameters are set to "clear" by default, the output module turns off the outputs at an error. If it is
required to hold the output to operate the system safely, set the parameters to "hold".
(3) When the output is set to "hold" with the Q4ARCPU (stand-alone system) and the A6RAF
(redundant system), the remote I/O station turns off all outputs. If it is required to hold the output to
operate the system safely, set the parameters of the remote I/O station to "hold".
● When connecting a peripheral with the CPU module or connecting an external device, such as a
personal computer, with an intelligent function module to modify data of a running programmable
controller, configure an interlock circuit in the sequence program to ensure that the entire system will
always operate safely. For other forms of control (such as program modification or operating status
change) of a running programmable controller, read the relevant manuals carefully and ensure that
the operation is safe before proceeding. Especially, when a remote programmable controller is
controlled by an external device, immediate action cannot be taken if a problem occurs in the
programmable controller due to a communication failure. To prevent this, configure an interlock circuit
in the sequence program, and determine corrective actions to be taken between the external device
and CPU module in case of a communication failure.
● If a communication cable is disconnected, the network may be unstable, resulting in a communication
failure of multiple stations. Configure an interlock circuit in the sequence program to ensure that the
entire system will always operate safely even if communications fail. Failure to do so may result in an
accident due to an incorrect output or malfunction.
CAUTION
● Always reset the CPU module after changing the parameters for the CPU module or the remote I/O
module. Failure to do so, data before the change may cause malfunction.
● Do not install the control lines or communication cables together with the main circuit lines or power
cables. Keep a distance of 100mm or more between them. Failure to do so may result in malfunction
due to noise.