New and Original Mitsubishi PLC A1SY42

Mitsubishi A1SY42 | MELSEC-A Slim 64-Point Transistor Sink Output — 12/24VDC / 0.1A per Point / 1.6A Common / 2ms / 40-Pin FCN

64 Transistor Outputs in One A1S Slim Slot

The A1SY42 provides the highest transistor output point density in the MELSEC-A A1S slim series — 64 NPN outputs from a single rack slot. For comparison, the A1SY41 provides 32 points in the same slot format. When a control system must command many discrete field devices — solenoid valves, relay coils, pilot lamps, motor starter enables — from an MELSEC-A rack, the A1SY42's 64-point density maximises output capacity while minimising the number of rack slots consumed.

All 64 channels connect through a single 40-pin FCN-type connector. Field wiring runs via FCN cable assembly to a separate terminal board where individual conductors terminate at screw terminals — the wiring approach standard across the MELSEC-A A1S output module family.

Key Specifications

A1SY42 in the MELSEC-A Output Module Family

The A1SY42 maximises channel count at the 0.1A current level. For fewer points at higher current, the A1SY50 or A1SY60 apply. This session has previously described the A1SX41 (digital input) and A1S68DAI (analogue output) for the same A1S platform — the A1SY42 completes the basic digital output capability for the same rack.

Common Current Limit — 1.6A Per Group

At 0.1A per point, 16 simultaneous fully loaded outputs would reach 1.6A — the common limit. In practice, most field devices draw considerably less:

• 24VDC relay coil: 30–60mA → 26 simultaneous fully loaded outputs per common
• 24VDC solenoid pilot: 80–150mA → 10–20 simultaneous
• 24VDC LED indicator: 20mA → 64 simultaneous within limit

For dense solenoid applications where many pilots fire simultaneously at high current, verify the total simultaneous common current against the 1.6A limit.

Application Scenarios

Dense valve panel: 64 pneumatic valve pilots at 24VDC. At 60mA per valve, all 64 = 3.84A total — distribute across commons correctly. One A1SY42 handles all valve outputs from one rack slot.

Machine status indicator panel: 64 LED pilot lights at 24VDC, 20mA each. All simultaneous = 1.28A — within limit. One module controls the complete status display.

Multi-zone relay driving: 64 output channels driving 24VDC relay coils at 30–50mA each. Used in large control panels where outputs activate field relays for higher-voltage loads.

FAQ

Q1: What is the difference between A1SY42 and A1SY42P?

The A1SY42P adds per-common fuse protection for each common terminal group. A field wiring short circuit on the A1SY42P blows the local fuse for that common group, leaving other commons operational. The A1SY42 has no such protection. In installations where field wiring faults are a maintenance concern, the A1SY42P is the more robust specification.

Q2: Is the A1SY42 compatible with full-size A-series racks (A2U, A3U)?

No. The A1SY42 is the A1S slim format — it fits only A1S slim racks. Full-size A-series racks use physically larger modules. The full-size equivalent for 64-point transistor output in the A-series is the A2Y42. Confirm the rack format from the installed hardware before ordering.

Q3: How is field wiring connected to the 40-pin FCN connector?

Via FCN cable assembly — a multi-conductor cable with a 40-pin FCN plug on the module side and a terminal board (such as A1TBN or compatible) on the field side. The terminal board provides individual screw terminals for each channel and common. This wiring approach is detailed in the MELSEC-A hardware manual under the A1SY42 installation section.

Q4: What programme addresses control the A1SY42 outputs?

Y-device addresses in the MELSEC-A CPU's output image area. The GX Developer or GX Works2 hardware configuration (for the AnS/A1S CPU type) assigns the starting Y address for each module based on slot position. Standard ladder Y coil, SET, and RST instructions command the outputs at the assigned addresses.

Q5: How does the A1SY42 compare to the A1SY81 (32-point) in terms of selection?

The A1SY81 provides 32 outputs at 0.1A per point with 2A per common — more current headroom per common than the A1SY42's 1.6A. The A1SY42 doubles the point count to 64 but at 1.6A per common. Choose A1SY81 when simultaneous current density per common is higher; choose A1SY42 when maximum channel count per slot is the priority and the common current budget is manageable.