Precautions For Online Module Change; Precautions Before Module Change - Mitsubishi Electric MELSEC-Q Series User Manual

7 ONLINE MODULE CHANGE

7.4 Precautions for Online Module Change

7.4.1 Precautions before module change

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This section lists precautions for changing a module online.
(1) Perform an online module change following the correct procedure. Not doing so
may cause malfunction or failure.
(2) Even if pre-recorded data are set to the buffer memory in the module that was
changed online and control is restarted, control cannot be restarted in the same
control status since the data in Manipulated value (MV) (buffer memory address:
13, 14) is cleared once control is stopped
(3) Even if an alert occurs before performing an online module change, the same
alert does not necessarily occur when the control is restarted. For example, if an
upper limit alert with wait is set and the alert occurs before performing an online
module change, the module goes into the wait status and the alert does not
occur when the control is restarted after performing the online module change.
(1) Stopping module operation
Turn off the following output signals and stop module operation before changing
a module.
Device No.
Yn1
Yn8
Yn9
YnB
REMARKS
Control may not stop even when Setting/operation mode command (Yn1) is turned
off.
To stop control without fail, set 0 (Stop) in PID continuation flag (buffer memory
address: 169) and turn off Setting/operation mode command (Yn1).
The stop status can be checked with Setting/operation mode status (Xn1) (off: Stop).
(2) Continuing control
Set 1 (Continue) in PID continuation flag (buffer memory address: 169) before
performing an online module change to continue control in the module until it is
removed even during the online module change.
Shut off the external power supply (all phases) and ensure safety before
removing a module.
Signal name
Setting/operation mode command (Refer to the REMARKS
below.)
FeRAM backup start command
Default setting registration start command
Setting change command
MELSEC-Q
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