Mitsubishi MELSEC-Q Series User Manual page 5

[Design Precautions]
DANGER
When overcurrent which exceeds the rating or caused by short-circuited load flows in the output
module for a long time, it may cause smoke or fire. To prevent this, configure an external safety
circuit, such as fuse.
Build a circuit that turns on the external power supply when the programmable controller main
module power is powered on.
If the external power supply is turned on first, it could result in erroneous output or erroneous
operation.
When there are communication problems with the data link, refer to the corresponding data link
manual for the operating status of each station.
Not doing so could result in erroneous output or erroneous operation.
When connecting a peripheral device to the CPU module or connecting a personal computer or the
like to the intelligent function module / special function module to exercise control (data change) on
the running programmable controller, configure up an interlock circuit in the sequence program to
ensure that the whole system will always operate safely.
Also before exercising other control (program change, operating status change (status control)) on
the running programmable controller, read the manual carefully and fully confirm safety.
Especially for the above control on the remote programmable controller from an external device, an
immediate action may not be taken for programmable controller trouble due to a data communication
fault.
In addition to configuring up the interlock circuit in the sequence program, corrective and other
actions to be taken as a system for the occurrence of a data communication fault should be
predetermined between the external device and programmable controller CPU.
CAUTION
Do not bunch the control wires or communication cables with the main circuit or power wires, or
install them close to each other.
They should be installed 100 mm (3.94 inch) or more from each other.
Not doing so could result in noise that would cause erroneous operation.
When controlling items like lamp load, heater or solenoid valve using an output module, large current
(approximately ten times greater than that present in normal circumstances) may flow when the
output is turned OFF to ON.
Take measures such as replacing the module with one having sufficient rated current.
A
- 3