Power Supply Sequence And Handling Of I/O Data - Mitsubishi Electric MELSEC-Q Series User Manual

2.2.2

Power supply sequence and handling of I/O data

An incorrect input/output may occur depending on the supply procedure of the power of the programmable controller,
the 24VDC external power supply for transmission lines, and the 24VDC external power supply for slave module. Note
the following points.
• Do not make any access related to the master module (X, Y, or FROM/TO) for 2 seconds after the
programmable controller is powered on. Doing so can cause a malfunction of the module.
• Power on the programmable controller and 24VDC external power supply in this order.
• Depending on how to supply the 24VDC external power supply, D/G terminal disconnection (Xn4) may turn
on (the ALM LED may turn on) during initial processing. Therefore, turn on (500ms or more) and off
Disconnection flag reset command output (Yn0) at the start of access.
Power supply of
a programmable
controller
External power supply
Yn0
(Disconnection flag
reset command output)
Access
ON
2s or more
OFF
ON
OFF
ON
OFF
Execution
Stop
CHAPTER 2 SPECIFICATIONS
500ms or more
AND
condition
Access prohibited
2
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