Series-40M2

Supported Applications

The Series 40M2 Digital Temperature Controller by Dwyer, a DwyerOmega brand, is a versatile panel-mount device engineered for temperature measurement and control across heating, cooling, and refrigeration systems. It accepts a broad mix of sensor inputs and drives connected loads through both an integrated relay and a modulating output, making it suitable for equipment builders and OEMs who need a compact controller with flexible input and control options in a single package.

Because the controller accepts RTD, thermocouple, thermistor, current, and voltage inputs, it can be adapted to many process and appliance designs without changing hardware. A TTL/RS-485 serial interface with Modbus protocol allows the unit to be programmed or integrated into a building management system for supervisory monitoring and remote configuration. The multi-color LED display with alarm and output symbols gives operators clear at-a-glance status, and temperature units are field selectable between °F and °C.

Operating Conditions & Performance

The Series 40M2 supports temperature measurement and set points across ranges that depend on the selected sensor. Representative input ranges include -58 to 302°F (-50 to 150°C) for a PTC probe, -40 to 230°F (-40 to 110°C) for an NTC probe, -148 to 999°F (-100 to 537°C) for a PT100 or PT1000 probe, -112 to 572°F (-80 to 300°C) for a Ni120 probe, and -130 to 999°F (-90 to 537°C) for J-type and K-type thermocouples. Display resolution is 1°F (0.1°C) for thermocouples and for all other models.

The controller offers On-Off, PID, and PID with auto-tuning control. The primary K1 relay output is rated 16 A in-rush resistive @ 250 VAC, SPST, type 1, and a modulating 0-10 VDC or PWM output is available. A multipurpose dry contact is rated 3.3 V, 1 mA. Configurable analog inputs cover current at 0-20 mA or 4-20 mA and voltage at 0-10 V or 2-10 V.

Power requirements are 115-230 VAC or 12-24 VAC/DC depending on model. The operating ambient range is 23 to 131°F (-5 to 55°C) with a storage range of -13 to 158°F (-25 to 70°C), and humidity limits are 10-90% RH, non-condensing. The front panel carries an IP65 rating, the unit weighs 2.3 oz (65 g), and it measures 2-15/16 in (75 mm) wide, 1-5/16 in (33 mm) high, and 2-5/16 in (59 mm) deep. The controller carries CE, UKCA, and cURus approvals.

Configuration Options

The two catalog models are distinguished by their power supply. The 40M2-20 is powered from 115-230 VAC line voltage, while the 40M2-40 operates from a 12-24 VAC/DC supply. Both share the same sensor input set, display, relay, and Modbus communication capabilities.

One functional difference follows from the low-voltage supply: the 12-24 VAC/DC model must be powered at 24 VAC/DC in order to provide the 0-10 VDC or PWM modulating output. This makes the supply selection a meaningful design decision when the modulating output is required rather than only the relay.

Key Product Differences

The series is ordered by appending a power-supply suffix to the base model number, following the guide 40M2 - Power Supply.

• 40M2-20 — 115-230 VAC power supply.
• 40M2-40 — 12-24 VAC/DC power supply.

A range of accessories extends the controller for programming and sensing:

• 40X2-K — 40M2/T2 programming key.
• TCS-J — J type thermocouple, 4" probe, 48" extension.
• TCS-K — K type thermocouple, 4" probe, 48" extension.
• TS-1 — PTC sensor, brass sheath, PVC cable, 5 ft. (1.5 m) length.
• TS-2 — PTC sensor, SS sheath, PVC cable, 5 ft. (1.5 m) length.
• TS-7 — NTC sensor, no sheath, PVC cable, 5 ft. (1.5 m) length.