High-speed counting for the FX3U platform
The FX3U-4HSX-ADP is a 4-channel high-speed input adapter for Mitsubishi Electric's FX3U series PLCs, accepting differential line-driver signals (equivalent to AM26C32) for encoder or pulse-train inputs up to 200 kHz in 1-phase mode and 100 kHz in 2-phase quadrature mode. Each channel is optically isolated from the PLC backplane via photocouplers, and the input voltage is DC 5 V — matching standard differential encoder outputs. The adapter draws 30 mA from both the DC 5 V and DC 24 V internal PLC supplies.
Counting range and I/O mapping
The hardware counter supports a signed 32-bit count range from -2,147,483,648 to +2,147,483,647, with count direction and comparison output handled by the sequence program. The adapter occupies four input points on the base unit: connecting the first adapter uses X000–X002 and X006; a second adapter uses X003–X005 and X007. A function expansion board is required on the base PLC when also connecting analog or communication adapters, but not when only the high-speed input/output adapter is used.
Grounding and environmental limits
Class D grounding (grounding resistance 100 Ω or less) is specified, with the instruction that grounding should be dedicated or common — not shared with high-noise equipment. The withstand voltage between the high-speed input terminals and the PLC earth terminal is AC 500 V for 1 minute; insulation resistance is 5 MΩ or more at DC 500 V. Operating ambient temperature is 0 to 55 °C, storage -25 to 75 °C, with 5 to 95% RH non-condensing. The adapter is not rated for use above 2000 m altitude or in atmospheres with corrosive gas or conductive dust.
Lifecycle and sourcing
The FX3U-4HSX-ADP is in a mature lifecycle stage — still available through distribution channels, not marked for discontinuation. No official successor or cross-reference to the LJ71E71-100 or FX5-CCLGN-MS exists; those are different-function modules (Ethernet and CC-Link respectively) and do not drop in as replacements.