2-axis servo positioning via SSCNET III
The FX3U-20SSC-H is a positioning block that controls two servo axes over the SSCNET III fiber-optic servo bus — the same network used across Mitsubishi's MR-J4 and MR-JE drive families. That means the drive selection is locked to SSCNET III-compatible amplifiers; a standard pulse-train or analog servo won't talk to this module. Scan cycle runs at 1.77 ms, which sets the position-loop update rate. For a two-axis interpolated move, that's tight enough for most pick-and-place or indexing stations, but if you're chasing sub-millisecond cam profiles, the cycle time becomes the ceiling.
Power budget and I/O footprint
Draws 100 mA from the 5 V DC PLC backplane plus 220 mA from a 24 V DC auxiliary supply (5 W total). The 24 V rail needs to be within +20%/-15% of nominal with ripple under the stated limit — a shared supply with solenoids or contactors can bounce the rail enough to fault the module. Occupies 8 I/O points on the FX3U base rack, counted as either input or output depending on the system configuration. That's one slot's worth of address space — plan the I/O map accordingly.
Parameter backup and lifecycle
Positioning parameters, servo parameters, and table data can be saved to internal flash memory rated for 100,000 write cycles. That's enough for frequent recipe changes or tuning iterations over the machine's life, but not a continuous data-logging target.