Mitsubishi Electric MELSEC-Q Series User Manual page 77

(c) When plugging the extension cable to any base unit, hold the
connector part of the extension cable.
(d) After fitting the extension cable, always tighten the extension
cable connector fixing screws.
(Tightening torque: 20N•cm)
(3) Disconnection of extension cable
When unplugging the extension cable, hold and pull the connector
part of the extension cable after making sure that the fixing screws
have been removed completely.
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