Modicon M221 TM221M16R Logic Controller Schneider Electric

TM221M16R – Compact 16 I/O PLC with Relay Outputs and Dual Serial Ports

Product Introduction

The TM221M16R belongs to the Modicon M221 series from Schneider Electric. This compact logic controller operates on a 24 V DC supply and provides 16 I/O points with relay outputs. It is the smallest member of the M221 family, measuring just 70 mm wide. Despite its small footprint, it offers 2 analog inputs, 4 fast counting inputs, and support for up to 14 remote expansion modules. This makes it an excellent choice for small machines, conveyor sections, pump stations, and HVAC control. The controller includes two non-isolated serial ports, giving you flexibility for connecting to HMIs, drives, and other Modbus devices.

Technical Specifications

Power Supply and Inputs

The TM221M16R runs on a 24 V DC supply with a range of 20.4 to 28.8 V. It consumes up to 22.5 W with a full expansion bus, or just 3.6 W without expansions. The power supply output delivers 0.52 A at 5 V and 0.46 A at 24 V for expansion modules. For discrete inputs, the unit offers 8 points that comply with IEC 61131-2 Type 1. These inputs support both sink and source wiring at 24 V DC. Among them, 4 inputs (I0, I1, I6, I7) are fast, with response times of just 5 µs. The controller also includes 2 analog inputs with a 0...10 V range and 10-bit resolution. Accuracy stays within ±1% of full scale.

Output Characteristics

This model features 8 relay outputs, normally open type. These relays handle voltages from 5...250 V AC and 5...125 V DC. Each output supports up to 2 A current, with a maximum of 7 A per common group. The relays are rated for various load types, including resistive and inductive. For example, resistive loads at 240 V/160 VA achieve 300,000 cycles. Inductive AC-15 loads at 240 V/36 VA also reach 300,000 cycles. Mechanical durability exceeds 20 million operations, so the relays last long in frequent switching applications. The minimum load requirement is 1 mA at 5 V DC, which suits dry contact applications.

Communication and Connectivity

The TM221M16R includes three communication options. First, a non-isolated serial link (Serial 1) with RJ45 and RS485 interface supports Modbus RTU/ASCII. Second, a second non-isolated serial link (Serial 2) with RJ45 and RS232/RS485 interface gives you an additional port for connecting a second HMI or drive. Third, a USB mini B port enables fast programming at 480 Mbit/s. Notably, this model does not include built-in Ethernet, so you need to use serial communication or add an optional gateway for network connectivity.

Expansion Capabilities

The TM221M16R supports up to 7 local expansion modules or 14 remote expansion modules via the serial link. This flexibility allows you to scale I/O as needed, from a small standalone machine to a distributed system with I/O spread across a production line. The expansion bus provides both 5 V and 24 V power for connected modules.

Memory and Performance

The controller stores programs in 256 kB of flash memory, handling up to 10,000 instructions. Execution time runs 0.3 ms per 1,000 instructions for event and periodic tasks, and 0.7 ms for other instructions. Boolean instructions execute in 0.2 µs. The real-time clock drifts ≤30 s/month at 25 °C. For control loops, the unit supports up to 14 simultaneous PID regulators. The application structure includes 1 configurable master task, 1 cyclic auxiliary task, and 8 interrupt tasks, giving you flexibility for time-critical operations.

Mechanical and Environmental Specifications

Dimensions and Mounting

The TM221M16R measures 70 mm wide, 90 mm high, and 70 mm deep. It weighs just 0.264 kg, making it one of the lightest PLCs in its class. You can mount it on a DIN rail (TH35-7.5 or TH35-15) or secure it to a panel using the optional fixing kit. The compact size makes it ideal for small control cabinets and distributed installations where space is limited.

Environmental Ratings

Operating temperature ranges from -10...55 °C for horizontal mounting, or -10...35 °C for vertical installation. Storage temperature spans -25...70 °C. Humidity tolerance is 10...95% without condensation. With the protective cover fitted, the unit achieves an IP20 rating. Vibration resistance reaches 3.5 mm at 5...8.4 Hz and 1 gn at 8.4...150 Hz on both rail and panel mounting. Shock resistance is 98 m/s² (approx. 10 gn) for 11 ms.

Electrical Immunity

The TM221M16R complies with EN/IEC 61131-2 and EN/IEC 61010-2-201 standards. It holds certifications including DNV-GL, ABS, LR, cULus, RCM, EAC, CE, UKCA, and cULus HazLoc, making it suitable for marine, hazardous, and industrial locations. It withstands ESD up to 8 kV in air and 4 kV on contact. Fast transients up to 2 kV on power lines and relay outputs are tolerated. Surge immunity reaches 2 kV common mode on AC power lines and 0.5 kV on DC power lines. Radiated and conducted emissions meet EN/IEC 55011 Class A limits.

Installation and Wiring Guide

Mounting Instructions

First, select a clean, flat surface within your control panel. For DIN rail mounting, snap the controller onto the rail until you hear a click. Verify the rail conforms to IEC 60715 (TH35-7.5 or TH35-15). For panel mounting, use the optional fixing kit. Maintain at least 50 mm clearance above and below for proper airflow. Keep the unit away from high-voltage or high-temperature components.

Wiring Recommendations

The TM221M16R uses removable screw terminal blocks for both inputs (10 terminals) and outputs (11 terminals). Use shielded cables for fast inputs and keep lengths under 10 m. For standard inputs and outputs, unshielded cables up to 30 m are acceptable. Analog inputs require unshielded cables under 1 m for best accuracy. Connect the 24 V DC power supply (20.4...28.8 V) to the 3-terminal block. The sensor supply provides 24 V DC at 250 mA for external devices.

Relay Output Protection

The relay outputs include no built-in protection at 5 A. For inductive loads (e.g., contactors, solenoids, motors), add external snubber circuits or varistors across the load to suppress voltage spikes. This practice extends relay contact life and reduces electrical noise. For DC inductive loads, add a flyback diode across the load. For AC loads, use an RC snubber or MOV.

Serial Communication Wiring

The two serial ports (RS485 and RS232/RS485) support Modbus RTU/ASCII. For RS485 networks, use shielded twisted-pair cable and maintain a maximum bus length of 15 m at 115.2 kbit/s. Terminate both ends of the bus with 120Ω resistors to prevent reflections. For RS232 connections, keep cable length under 3 m.

Packaging List

When you receive the TM221M16R, the package includes the following items:

• 1 x TM221M16R logic controller unit

• 1 x removable screw terminal block for inputs (10 terminals)

• 1 x removable screw terminal block for outputs (11 terminals)

• 1 x 3‑terminal block for 24 V DC power connection

• 1 x 4‑terminal block for analog inputs

• 1 x protective cover (pre-installed)

• 1 x quick start guide (printed)

Note: The SD card, programming cable (USB mini B), and DIN rail mounting accessories are sold separately. For shipping, we use FedEx, UPS, or DHL depending on your region.

Frequently Asked Questions (FAQ)

1. Does the TM221M16R have built-in Ethernet?
No. This model includes two serial ports (RS485 and RS232/RS485) and a USB port, but no Ethernet. You can add Ethernet connectivity using an external gateway or choose another M221 model like the TM221CE40R which includes built-in Ethernet.

2. Can I expand the I/O beyond the built-in 16 points?
Yes. The TM221M16R supports up to 7 local expansion modules directly attached, or up to 14 remote expansion modules connected via the serial link. This gives you significant flexibility for system growth.

3. What is the difference between Serial 1 and Serial 2?
Serial 1 is an RS485 port only. Serial 2 is a combined RS232/RS485 port that you can configure for either protocol. Both support Modbus RTU/ASCII master or slave operation, giving you two independent communication channels.

4. What software do I need to program this controller?
Use EcoStruxure Machine Expert – Basic (formerly SoMachine Basic). This free software supports the entire M221 series and offers ladder logic, function block diagram, and instruction list programming. The USB port provides a direct connection for fast downloads.

5. Is this PLC suitable for marine applications?
Yes. The TM221M16R holds marine certifications including DNV-GL, ABS, and LR. It also meets conducted disturbance requirements for marine specifications (LR, ABS, DNV, GL). The unit is rated for operation in ordinary and hazardous locations.