[Design Precautions]
!
DANGER
• When controlling a programmable controller (modifying data) in operation by connecting
computer peripheral devices to the CPU module or connecting personal computers to the
intelligent function modules, configure an interlocking circuit in a sequence program so that the
safety of the overall system is maintained. Also, before performing other control operations
(program modifications and operating-status modifications (status control)) on the
programmable controller in operation, be sure to read the manual thoroughly and confirm the
safety. Especially in the above-mentioned control operations, which are performed from an
external device to a remote programmable controller, problems arising on the programmable
controller side may not be dealt with immediately due to abnormal data communication. In
addition to configuring an interlocking circuit in a sequence program, determine how the system
should handle data-communication errors between the programmable controller CPU and
external devices.
• Do not write any data in the "system area" of the buffer memory of the intelligent function
module.
Also, do not output (turn on) the "use prohibited" signal, which is one of the output signals from
the programmable controller CPU to the intelligent function module.
If data is written to the "system area" or the "use prohibited" signal is output, the programmable
controller system may malfunction.