What this slot is
The Mitsubishi FX1N-60MR-ES/UL is a main-unit PLC in the FX1N series, powered from 100-240V AC and rated for 35W internal consumption — so the panel feed is single-phase AC and the thermal budget is modest, not a multi-amp drive-grade load. I/O lands at 36 inputs against 24 outputs on the base unit, with a maximum of 60 total I/O when expansion is fitted; the outputs are relay-type, which is the right call for mixed contactor and solenoid loads in packaging-line and OEM machine work.
Second-source question — FX3U vs FX1N
For a closer functional match the FX2N-64MR-ES/UL sits at 32 inputs / 32 outputs on 100-240V AC — closer in I/O count to the FX1N's 60-point profile but still a different footprint and a different firmware generation, so it is a reference candidate rather than a confirmed cross.