Mitsubishi MELSEC-Q Series User Manual page 21

2 SYSTEM CONFIGURATION
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(b) Instantaneous power failure of remote I/O module
When instantaneous power failure occurs in the power source (24V DC) for
the remote I/O module, faulty data may be input.
1) Causes of faulty input due to instantaneous power failure
The hardware of the remote I/O module converts the supplied power of
24V DC into 5V DC inside the module and uses it for its own
operation.
When instantaneous power failure occurs in the remote I/O module,
the expression,
(Time until 5V DC is turned OFF inside the remote I/O module)
>(Response time from ON to OFF of the input unit), are formed.
Therefore, when the devices are refreshed within the time shown as
(1), data will be erroneously input. (Especially, when the input
response time is set to the high-speed response type)
Remote I/O module
(Power for module and
external supply power for input)
Remote I/O module
(5V DC)
Input (Xn)
Due to OFF of external supply
power for input detection,
input (Xn) turns OFF after
response time from ON to OFF
of Input unit.
MELSEC-Q
1)
Due to ON of external supply
power for input detection,
input (Xn) turns ON after
response time from OFF to ON
of input module.
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