Mitsubishi Electric MELSEC-A series User Manual page 38

When controlling a running programmable controller (data
DANGER
modification) by connecting a peripheral device to the CPU
module or a PC to a special function module, create an
interlock circuit on sequence programs so that the whole
system functions safely all the time.
Also, before performing any other controls (e.g. program
modification, operating status change (status control)), read
the manual carefully and ensure the safety.
In these controls, especially the one from an external device
to a programmable controller in a remote location, some
programmable controller side problem may not be resolved
immediately due to failure of data communications.
To prevent this, create an interlock circuit on sequence
programs and establish corrective procedures for
communication failure between the external device and the
programmable controller CPU.
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.
When using the extension base unit, A1S52B, A1S55B or
A1S58B, attach the included dustproof cover to the module
in slot 0.
Otherwise, internal parts of the module may be flied in the
short circuit test or when an overcurrent or overvoltage is
accidentally applied to external I/O section.
Do not install the control lines or communication cables
CAUTION
together with the main circuit or power lines, or bring them
close to each other.
Keep a distance of 100mm (3.9inch) or more between them.
Failure to do so may cause malfunctions due to noise.
When an output module is used to control the lamp load,
heater, solenoid valve, etc., a large current (ten times larger
than the normal one) may flow at the time that the output
status changes from OFF to ON. Take some preventive
measures such as replacing the module with the one of a
suitable current rating.
24