8.1.6 Environmental Problem
If the following improper operations occur in the controlled system, check possible environmental factors.
(1)If an improper operation occurs synchronously with the operation of I/O devices:
The noise generated at ON/OFF of the output device (load) may be the cause of the problem. Take necessary measures mentioned in section Precaution.
(2)If an improper operation occurs synchronously with the operation of surrounding equipment or high- frequency equipment:
The noise induced in I/O signal lines may be the cause of the problem. The surge voltage, voltage fluctuations, or differences of grounding potentials may cause the problem, depending on the power supply system or the grounding system. Check the operation in accordance with the precautions as maintained. For some cases, isolation from the ground may lead to the stable operation.
(3)If an improper operation occurs synchronously with the operation of machinery:
The vibration of the equipment may cause the problem. Check that the installation status of the units and take necessary measures.
(4)If a similar failure is repeated after the unit is replaced:
Check that no metal debris or water drops has been entered into the unit/module. Apart from the above points, consider climatic conditions. If the ambient temperature is beyond the specified range, stable operation of the system is not guaranteed.
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