Mitsubishi Melsec-L Series User Manual page 31

(b) At momentary power failure of remote I/O modules
If momentary power failure occurs in the power supplied to remote I/O modules (24VDC), incorrect input may
occur.
• Cause
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.
The hardware of a remote I/O module internally converts 24VDC (module power supply) into 5VDC.
If momentary power failure occurs in a remote I/O module, (Time until the internal power of the remote I/O
module (5VDC) turns off) > (Time until the input module turns off) is met.
Therefore, if data are refreshed within the time shown in 1) in the figure below, incorrect input may occur
(This situation especially occurs when the input response time is set to high-speed response).
Remote I/O module
(Module power supply and
input external power supply)
Remote I/O module
(Inside: 5VDC)
Input (Xn)
When the input external power
supply is turned off, the input (Xn)
turns off after the input module
turns off.
CHAPTER 5 SYSTEM CONFIGURATION
1)
When the input external power
supply is turned on, the input (Xn)
turns on after the input module
turns on.
5
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