What It Does and Where It Fits
The Mitsubishi FX3U-4AD-TC-ADP is a 4-channel thermocouple input adapter for FX3U, FX3UC, FX3G, and FX3GC series PLCs, accepting K or J type thermocouples with 200 µs per-channel conversion and ±0.5% FS + 1°C overall accuracy. It draws 15 mA from the 5 V backplane and 45 mA from a separate 24 VDC supply (+20%/-15%), so budget the external power rail before wiring. No channel-to-channel isolation exists, but the input section is optically isolated from the PLC and the power supply is isolated via DC/DC converter.
Grounding and Accuracy Notes
Class D grounding with resistance ≤ 100 Ω is specified; Mitsubishi calls for a dedicated or common ground circuit — share the ground with the PLC main unit if you must, but keep high-frequency drives off the same path. Resolution is 0.4°C for K-type and 0.3°C for J-type. The rated temperature range for K-type is -100 to +1000°C; overall accuracy is ±0.5% of full scale plus 1°C.
Lifecycle and Sourcing
Classified as a mature product — no imminent phase-out, so it remains a reliable BOM line item for existing FX3U-based panels.