Schneider Electric TM221C40R Modicon M221 PLC

The Schneider Electric TM221C40R is a Modicon M221 series programmable logic controller with 40 built-in I/O points. It features 24 digital inputs (24V DC) and 16 transistor or relay outputs (the "R" suffix indicates relay outputs). The controller operates on 24V DC and includes an embedded EtherNet/IP port for networking and programming, plus a serial line (RS-232/RS-485) for Modbus communication. The M221 is designed for small to medium machine control applications, offering high performance in a compact form factor. It is programmed using SoMachine Basic software, which supports ladder diagram (LD) and function block diagram (FBD).

Technical Specifications

Power supply: 24 V DC (20.4-28.8 V), consumption 20 W. I/O: 24 digital inputs (24V DC, sink/source, 4 mA), 16 relay outputs (2A at 30V DC / 250V AC, 2A per common). Program memory: 128 KB (flash). Execution time: 0.3 µs per boolean instruction. Built-in communication: Ethernet (10/100BASE-TX) for Modbus TCP and programming, serial line (RS-232/RS-485) for Modbus RTU or ASCII. USB port (mini-B) for programming. Real-time clock: battery-backed (optional). High-speed counter: up to 100 kHz, 2 channels. Pulse outputs: 2 channels, up to 100 kHz (for transistor models, but relay outputs cannot output high-speed pulses). Dimensions: 138 mm (H) × 90 mm (W) × 70 mm (D). Weight: 0.4 kg. Operating temperature: 0°C to 55°C. Storage: -25°C to 70°C. Protection: IP20. Certifications: CE, UL, CSA.

Key Features

• 40 I/O: 24 inputs, 16 relay outputs

• 24V DC power supply

• Embedded Ethernet port (Modbus TCP)

• Serial line (RS-232/485) for Modbus RTU

• High-speed counters (2 channels, 100 kHz)

• Real-time clock option

• SoMachine Basic programming (LD, FBD)

• Expandable with up to 7 TM3 expansion modules

Programming and Software

The TM221C40R is programmed using Schneider Electric SoMachine Basic (free download). The software supports Ladder (LD) and Function Block Diagram (FBD). It includes a library of functions (timers, counters, math, PID). The controller can also be configured via the embedded web server. The Ethernet port allows remote access and programming over the network.

Applications

The M221 series is used in small packaging machines, conveyors, pumps, fans, and HVAC systems. The relay outputs are suitable for switching contactors, solenoids, and indicator lights. The high-speed inputs can be used for encoder feedback or high-speed counting.

Installation and Wiring

Mount the controller on a 35 mm DIN rail. Connect 24V DC power to the V+ and 0V terminals. Inputs: connect sensors between input terminal and common (COM). Outputs: relay outputs – connect load between output terminal and power source (AC or DC). Each output group has a common terminal; use external fuses. The Ethernet port is an RJ45; use standard patch cable. The serial port is a 9-pin D-sub (male). The USB port is mini-B for programming. The module can be expanded by attaching TM3 expansion modules on the right side.

Maintenance and Troubleshooting

LEDs: PWR (green), RUN (green), ERR (red), I/O status (yellow). If the ERR LED is on, check the program or communication. The controller stores diagnostic information accessible via SoMachine Basic. The real-time clock battery (if installed) should be replaced every 5-7 years.

Conclusion

The Schneider TM221C40R Modicon M221 PLC offers a compact, cost-effective solution for small automation projects with its 40 I/O, relay outputs, and EtherNet/IP connectivity. It is suitable for OEMs and machine builders requiring flexible control in a small footprint.