M91-2-R34 Unitronics M91 Textual display and keyboard HMI and PLC onboard I/Os expands up to 150 I/Os

Why Choose the Unitronics M91-2-R34 Micro PLC with Integrated Text HMI?

The Unitronics M91-2-R34 is a powerful micro PLC with integrated text-based HMI from the Unitronics M90/M91 series, designed for reliable control of small and medium industrial automation systems. By integrating the controller, operator interface and onboard I/O within a single compact unit, it simplifies panel wiring and reduces overall system cost.

The controller features a built-in two-line LCD display with 16 characters per line and a 15-key operator keypad. This allows operators to view machine status, configure parameters and navigate menus directly on the device without the need for an external HMI panel.

The M91-2-R34 offers extensive onboard I/O including digital inputs, analogue inputs and relay outputs. Several inputs can also operate as high-speed counters or encoder inputs, enabling the controller to support motion monitoring and frequency measurement tasks.

Key Features

• All-in-one PLC with integrated text HMI and keypad.
• 2-line LCD display with 16 characters per line.
• 20 digital inputs configurable as PNP or NPN.
• 2 analogue inputs supporting voltage or current signals.
• 3 high-speed counter / encoder inputs for motion or frequency measurement.
• 12 relay outputs for switching industrial loads.
• RS232 and RS485 communication supporting Modbus protocols.
• I/O expansion port for connecting additional modules.

Technical Specifications

• Manufacturer: Unitronics
• Series: M90 / M91
• Model: M91-2-R34
• Controller type: Micro PLC with integrated text HMI
• Display: LCD text display
• Display size: 2 lines × 16 characters
• Keypad: 15 operator keys
• Digital inputs: 20 inputs
• High-speed inputs: up to 3 counter / shaft-encoder inputs
• Analogue inputs: 2 inputs (0–10 V, 0–20 mA, 4–20 mA)
• Relay outputs: 12 SPST-NO relay outputs
• Communication ports: RS232 / RS485
• Programming capacity: approx. 36 kB ladder logic
• Supply voltage: 24 V DC
• Expansion capability: supports I/O expansion modules
• Mounting: Panel mount or DIN rail
• Protection rating: IP65 front panel
• Operating temperature: 0 °C to 50 °C

Typical Applications

• Small machine automation systems.
• Water treatment and pump control.
• Packaging and material handling machinery.
• Industrial process monitoring and control.
• Standalone automation systems with local operator interface.

Trusted by Machine Builders

Unitronics M90 and M91 PLCs are widely used in industrial automation because they combine programmable control, operator interface and communications within a compact and cost-effective controller platform.