A - 1 A - 1
• When changing data of a running programmable controller from a peripheral connected to the
CPU module or from an external device such as a personal computer connected to an intelligent
function module, configure an interlock circuit in the program to ensure that the entire system
will always operate safely.
For other controls to a running programmable controller (such as program modification or
operating status change), read relevant manuals carefully and ensure the safety before the
operation.
Especially, in the case of a control from an external device to a remote programmable controller,
immediate action cannot be taken for a problem on the programmable controller due to a
communication failure.
To prevent this, configure an interlock circuit in the program, and determine corrective actions to
be taken between the external device and CPU module in case of a communication failure.
• 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 CPU module 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.