Mitsubishi Electric MELSEC Q Series User Manual page 4

[Design Precautions]
● In an output circuit, 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.
● When there are communication problems with the data link, refer to the corresponding data link
manual for the operating status of each station. Incorrect output or malfunction may result in an
accident.
● When connecting a peripheral device to the CPU module or connecting a personal computer or the
like to the intelligent function module to exercise control (data change) on the running C Controller
module, configure up an interlock circuit in the user 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 C Controller module, read the manual carefully and fully
confirm safety. Especially for the above control on the remote C Controller module from an external
device, an immediate action may not be taken for C Controller module trouble due to a data
communication fault. In addition to configuring up the interlock circuit in the user 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 CPU module.
● Do not write data into the write-protected area within the intelligent function module buffer memory.
Further, do not output (ON) prohibited signals in the output signals from the CPU module to the
intelligent function module. Writing data to the write-protected area or output of prohibited signals
may cause malfunction of the C Controller system.
● For the write-protected area and prohibited signals, refer to the User's Manual for each intelligent
function module.
● If the communication cable is disconnected, the line becomes unstable and any communication
problem may occur in multiple stations of the network. Even if any network communication problem
occurs in the multiple stations, configure up an interlock circuit in the user program to ensure safe
operation of the system. Failure to do so may result in an accident due to an incorrect output or
malfunction.
● In the refresh parameter settings, "Y" cannot be specified for link output (LY) refresh device and
remote output (RY) refresh device. Therefore, the device prior to STOP remains in the event of CPU
STOP.
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WARNING