Mitsubishi Electric MELCEC Q Series User Manual page 4

[DESIGN PRECAUTIONS]
WARNING
Configure a circuit so that the programmable controller is turned on first and then the external power
supply. If the external power supply is turned on first, an accident may occur due to an incorrect
output or malfunction.
For the operating status of each station after a communication failure, refer to relevant manuals for
the network.
Incorrect output or malfunction due to a communication failure may result in an accident.
When controlling a running programmable controller from a peripheral connected to the CPU module
or from a personal computer connected to a special function module, configure an interlock circuit in
the sequence program to ensure that the entire system will always operate safely.
For program modification and operating status change, read relevant manuals carefully and ensure
the safety before operation.
Especially, in the case of a control from an external device to a remote programmable controller,
immediate action cannot be taken for a problem on 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.
When setting up the system, do not allow any empty slot on the base unit.
If any slot is left empty, be sure to use a blank cover (A1SG60) or a dummy module (A1SG62) for it.
Otherwise, internal parts of the module may be flied in the short circuit test or when an overcurrent or
overvoltage is accidentally applied to the external I/O section.
CAUTION
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.
When a device such as a lamp, heater, or solenoid valve is controlled through an output module, a
large current (approximately ten times greater than normal) may flow when the output is turned from
off to on.
Take measures such as replacing the module with one having a sufficient current rating.
After the CPU module is powered on or is reset, the time taken to enter the RUN status varies
depending on the system configuration, parameter settings, and/or program size.
Design circuits so that the entire system will always operate safely, regardless of the time.
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