Mitsubishi Electric Q12DCCPU-V User Manual page 4

[Design Precautions]
(3) Outputs may remain on or off due to a failure of an output module relay or transistor.
Configure an external circuit for monitoring output signals that could cause a serious accident.
In an output module, when a load current exceeding the rated current or an overcurrent caused by a
load short-circuit flows for a long time, it may cause smoke and fire. To prevent this, configure an
external safety circuit, such as a fuse.
Configure a circuit so that the C Controller system 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 the relevant manuals
for the network.
Incorrect output or malfunction may result in an accident.
For the following controls, configure an interlock circuit in the user program to ensure that the entire
system will always operate safely.
(1) Changing data of a running C Controller module from the development environment (personal
computer) connected
(2) Changing the operating status
(3) Operation from the development environment (personal computer)
Especially, in the case of a control from an external device to a remote C Controller module,
immediate action cannot be taken for a problem on the C Controller module due to a communication
failure.
To prevent this, configure an interlock circuit in the user program, and determine corrective actions to
be taken between the external device and C Controller module in case of a communication failure.
To maintain the safety of the C Controller system against unauthorized access from external devices
via the network, take appropriate measures. To maintain the safety against unauthorized access via
the Internet, take measures such as installing a firewall.
When configuring the system, do not leave any slot empty on the base unit.
If a slot is to be left empty, attach a blank cover (QG60).
Failure to do so may cause internal parts of the mounted modules to fly apart during a short-circuit
test or when an excess current or voltage is applied to an external I/O part by mistake.
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WARNING