Mitsubishi Q2ASCPU User Manual page 49

(3) Grounding
CAUTION
(a) Carry out the independent grounding if possible. (Grounding resistance
100 or less.)
(b) If the independent grounding is impossible, carry out the shared
grounding (2) as shown below.
Programmable
controller
Class 3
grounding
(1) Independent grounding.....Best
(c) Use the cable of 2mm
Set the grounding point closer to the programmable controller to make
the grounding cable short as possible.
(d) If a malfunction occurs due to earthling, separate either LG or FG of the
base module, the device combination, or all the connection from the
earthling.
Be sure to ground the FG terminals and LG terminals to
the protective ground conductor. Not doing so could result
in electric shock or erroneous operation.
Other
Programmable
device
controller
(2) Shared grounding.....Good
2
or more for grounding.
Other
device
Class 3
grounding
(3) Common grounding.....Not allowed
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Other
Programmable
controller device