Mitsubishi Melsec PLC System with A61P, A2NCPU, AJ71C24, AX81, AY81
This Melsec system comprises five key modules that together form a complete programmable logic controller solution for medium-scale industrial automation. The set includes the A61P power supply unit, the A2NCPU main processor, the AJ71C24 serial communication module, the AX81 DC input unit, and the AY81 transistor output unit. All modules are designed to mount on a standard Melsec A-series base rack, providing a robust and reliable control platform.
A61P Power Supply Unit
The A61P is a power supply module providing 5 VDC (8 A) and 24 VDC (0.5 A) to the PLC rack. It accepts 100–240 VAC input and includes overvoltage and overcurrent protection. An LED indicator shows output status. Operating temperature: 0–55°C.
A2NCPU Central Processing Unit
The A2NCPU is a high-performance CPU for the AnS series, featuring 28K steps of program memory and a basic instruction speed of 0.3 µs. It supports up to 1024 I/O points and includes a built-in RS-422 programming port. The CPU also has a real-time clock and battery-backed RAM for data retention. It is compatible with Melsec networking via optional modules.
AJ71C24 Communication Module
The AJ71C24 is a serial communication module providing two independent RS-232C channels (one 25-pin, one 9-pin). It supports Mitsubishi's dedicated protocol (MC protocol) for communication with HMIs, printers, and other PLCs. Baud rates up to 19.2 kbps are selectable via DIP switches. The module also supports non-procedural communication for custom ASCII data exchange.
AX81 DC Input Module
The AX81 is a 16-point digital input module accepting 24 VDC (sink/source). It features optocoupler isolation, LED status indicators per channel, and a response time of 1.5 ms. The module is suitable for connecting pushbuttons, limit switches, and proximity sensors.
AY81 Transistor Output Module
The AY81 provides 16 transistor outputs (NPN, 24 VDC, 0.5 A per point) for driving solenoids, relays, and indicator lights. Short-circuit protection and LED indication are included. The module has a common terminal for each group of 8 outputs.
System Integration
This set is designed for easy assembly: the A61P occupies the leftmost slot, followed by the A2NCPU, then the AJ71C24, and finally the I/O modules. All components are powered from the backplane. Programming is performed using GX Developer or GX Works2 via the CPU's RS-422 port. The system supports up to 8 expansion racks.
Applications
Common uses include small to medium machine control, conveyor systems, and packaging lines. The combination offers a balanced mix of processing power, communication, and I/O capacity for a wide range of industrial tasks.
