MELSEC-Q QD75D Positioning Module Hardware Upgrade Technical Bulletin

This technical bulletin announces a hardware upgrade for Mitsubishi MELSEC-Q Series positioning modules (QD75D1, QD75D2, QD75D4) manufactured from January 2002, which adds a differential driver common terminal to the external interface to improve signal stability by eliminating potential differences with the driver unit. The document specifies target models by serial number (first six digits 040114 or higher) and notes that older versions remain usable without modification.