M91-2-R1 Unitronics M91 Textual display and keyboard HMI and PLC onboard I/Os expands up to 150 I/Os

Why Choose the Unitronics M91-2-R1 Micro PLC with Integrated Text HMI?

The Unitronics M91-2-R1 is a compact micro PLC with integrated text-based HMI from the Unitronics M90/M91 series, designed for small to medium industrial automation systems. The controller integrates logic control, operator interface and onboard I/O in a single unit, making it an efficient solution for machine builders and industrial control applications.

The controller features a two-line LCD operator display capable of showing 16 characters per line, along with a built-in 15-key keypad that allows operators to monitor and control machine processes directly from the panel. This integrated interface eliminates the need for a separate HMI panel while reducing panel space and wiring complexity.

The M91-2-R1 includes onboard digital and analogue I/O and supports additional expansion modules through its I/O expansion port. This flexibility allows the controller to scale as system requirements grow while maintaining a compact and cost-effective automation platform.

Key Features

• All-in-one PLC with integrated text HMI and keypad interface.
• 2-line LCD display with 16 characters per line.
• 10 digital inputs configurable as PNP or NPN.
• 3 inputs capable of high-speed counter / encoder functions.
• 1 analogue input supporting voltage or current signals.
• 6 relay outputs for switching industrial loads.
• RS232 and RS485 communication supporting Modbus protocols.
• I/O expansion port for adding additional modules.

Technical Specifications

• Manufacturer: Unitronics
• Series: M90 / M91
• Model: M91-2-R1
• Controller type: Micro PLC with integrated text HMI
• Display: Monochrome LCD
• Display size: 2 lines × 16 characters
• Keypad: 15 operator keys
• Digital inputs: 10 inputs (PNP/NPN configurable)
• High-speed inputs: Up to 3 counter or shaft-encoder inputs
• Analogue inputs: 1 input (0–10 V, 0–20 mA, 4–20 mA, 10-bit)
• Relay outputs: 6 SPST-NO relay outputs
• Relay rating: up to 5 A resistive load
• Communication ports: RS232 / RS485
• Programming capacity: approx. 36 kB ladder logic memory
• Supply voltage: 12 / 24 V DC
• Mounting: Panel mount or DIN rail
• Protection rating: IP65 / NEMA 4X (panel mounted)
• Operating temperature: 0 °C to 50 °C

Typical Applications

• Small machine automation systems.
• Water treatment and pump control systems.
• Industrial process monitoring.
• Packaging and material handling machines.
• Standalone control systems requiring simple HMI interaction.

Trusted by Machine Builders

Unitronics M90 and M91 controllers are widely used in industrial automation because they combine PLC control and operator interface in a compact, cost-effective device suitable for small and medium control systems.