What It Is – 4-Axis Positioning Over SSCNET
Mitsubishi QD75MH4 is a Q Series positioning module controlling up to four axes via SSCNET high-speed serial link, driving MR-J3-B servo amplifiers. Operation cycle clocks at 1.77 ms — half the time of the predecessor model — so positioning updates come twice as fast on the same backplane. Each axis stores 600 positioning data points, enough for complex point-to-point sequences without external lookup. The forced stop input is a single 24 VDC point per module, and the external signal interface handles upper/lower stroke limits, proximity dog, stop, speed/position switching, plus a manual pulse generator with A/B phase at 5 VDC.
How It Stacks Against the FX5-40SSC-S
The FX5-40SSC-S is the closest functional peer — also 4 axes, same 1.777 ms cycle, 600 data/axis, and similar linear/circular interpolation. But the QD75MH4 mounts on a Q Series rack with SSCNET; the FX5-40SSC-S uses the FX5 backplane and a different protocol. They are not drop-in interchangeable — different form factor, different bus. If you’re replacing an existing Q Series positioner, the QD75MH4 is a direct fit; the FX5 part requires a platform change.