Description
Detailed parameter table
| Parameter name | Parameter value |
| Product model | Metso IOP304 |
| Manufacturer | Metso Outotec Corporation |
| Product category | Entry-Level Analog Input Module (for Sensor Signal Acquisition) |
| Input Signals | Compatible with 4–20 mA current loops (standard industrial sensors: pressure transmitters, RTDs, thermocouples via signal conditioners); 0–10 VDC voltage signals (optional, via software config) |
| Number of Input Channels | 4 single-ended channels (shared common ground); Channel-to-channel isolation: 100 Vrms (basic noise protection) |
| Measurement Accuracy | ±0.2% of full scale (FS) at 25 °C; ±0.5% FS over operating temperature range (-10 °C to +55 °C); Resolution: 12 bits (sufficient for non-critical monitoring) |
| Communication Interface | Primary: Modbus RTU (RS-485, 9600–38400 baud, fixed parity: even); No optional protocols (optimized for simplicity) |
| Physical Dimensions | Ultra-compact DIN rail form factor: 22 mm (width) × 90 mm (height) × 65 mm (depth); Weight: ~180 g; IP Rating: IP20 (panel-mount, dust-protected only) |
| Environmental Requirements | Operating temperature: -10 °C to +55 °C (suitable for indoor, climate-controlled environments); Storage temperature: -20 °C to +60 °C; Relative humidity: 10%–90% (non-condensing); Vibration resistance: 0.3 g (10 Hz–500 Hz); Shock resistance: 15 g (11 ms half-sine) |
| Power Requirements | 24 VDC (18–30 VDC wide range); Power consumption: < 1.2 W (max, all channels active); No auxiliary sensor power output (uses external 24 VDC supply) |
| Safety & Compliance | CE (EN 61010-1); UL 61010-1 (Industrial Control Equipment); RoHS 2 compliant (lead-free); No hazardous area certification (not for Zone 2/22) |
| Compatibility | Works with Metso systems: Metso FieldCare Lite (simplified device management); Compatible with 3rd-party PLCs: Siemens S7-1200 (basic), Allen-Bradley Micro820, Schneider M208; Supports 24–18 AWG wire (stranded/solid) |
| Additional Features | LED indicators (1 power LED: green = on; 4 channel LEDs: green = signal detected); Non-removable terminal blocks (screw-type, tool-required); Factory-locked configuration (prevents accidental setting changes); Built-in overvoltage protection (30 VDC max per channel) |
METSO IOP304
Product introduction
The Metso IOP304 is an entry-level analog input module developed by Metso Outotec, engineered to simplify basic analog signal acquisition for small-scale industrial and commercial monitoring applications—from HVAC duct temperature tracking to water treatment tank level monitoring. Unlike higher-tier Metso modules like the Metso IOP320 (analog output, IP65) or Metso IOP331 (digital input, auxiliary power), the Metso IOP304 focuses on affordability and ease of use, making it ideal for users who need reliable sensor data without advanced features or ruggedness. Its core function is to convert analog signals from sensors (e.g., 4–20 mA pressure transmitters) into digital data, which is transmitted to a PLC or small DCS via Modbus RTU—enabling basic real-time monitoring and alerting.
As a foundational model in Metso’s entry-level I/O lineup, the Metso IOP304 excels in scenarios where simplicity and cost are prioritized. For example, a small office building uses the Metso IOP304 to monitor 4 HVAC zone temperatures: each channel connects to a 4–20 mA temperature transmitter, and the module sends data to a Siemens S7-1200 PLC via Modbus RTU. Unlike the Metso IOP320, which is built for harsh environments, the Metso IOP304 is optimized for indoor, climate-controlled spaces—its compact 22 mm width fits in tiny control panels, and its factory-locked configuration prevents accidental setup changes by untrained staff. Whether used in retail HVAC, small manufacturing, or municipal water treatment (indoor tanks), the Metso IOP304 delivers the reliability Metso is known for, packaged in a budget-friendly, easy-to-deploy design.
Core advantages and technical highlights
Ultra-Compact 22 mm Width for Tight Panel Spaces: The Metso IOP304’s 22 mm DIN rail width is 50% narrower than the Metso IOP331 (35 mm) and 60% narrower than the Metso IOP320 (50 mm)—critical for control panels with minimal space. A retail store’s HVAC contractor installs the Metso IOP304 in a 100 mm-wide panel (shared with a thermostat and relay): its slim profile allows all components to fit without expanding the panel size, cutting installation costs by $150 (vs. using a bulkier module). This space efficiency is unmatched by entry-level competitors, making the Metso IOP304 the top choice for retrofits or compact new builds.
Simplified Modbus RTU for Plug-and-Play Integration: The Metso IOP304 uses fixed Modbus RTU settings (9600–38400 baud, even parity) and works with Metso FieldCare Lite—a simplified software tool that eliminates complex configuration. A small water treatment plant technician sets up the Metso IOP304 in 15 minutes: after wiring 4 level transmitters, the technician uses FieldCare Lite to assign a Modbus address (1–247) and verify data transmission to an Allen-Bradley Micro820 PLC. Unlike modules with configurable parity or baud rates, the Metso IOP304’s fixed settings prevent setup errors—ideal for users with limited automation experience.
Cost-Effective Design for Budget-Constrained Projects: The Metso IOP304 is priced 40% lower than the Metso IOP331 and 60% lower than the Metso IOP320—enabling users to scale monitoring across multiple points without overspending. A bakery with 3 production lines uses 3 Metso IOP304 modules (1 per line) to monitor oven temperature (via 4–20 mA RTD transmitters): the total cost is 50% less than using one higher-tier module with extra channels, and the modules integrate seamlessly with a Schneider M208 PLC. This affordability does not compromise reliability—Metso’s quality control ensures the Metso IOP304 operates consistently for 5+ years in indoor environments.
Basic Overvoltage Protection for Sensor Safety: The Metso IOP304 includes 30 VDC overvoltage protection per channel—preventing damage from accidental sensor power surges (common in small facilities). A HVAC technician accidentally connects a 48 VDC sensor to the Metso IOP304: the module’s protection triggers, shutting down the channel temporarily instead of frying internal circuitry. After correcting the voltage, the Metso IOP304 resumes normal operation—avoiding a $200 replacement cost (vs. unprotected generic modules). This feature provides peace of mind for users new to wiring analog sensors.
Typical application scenarios
In HVAC commercial buildings, a 5-story office uses the Metso IOP304 to monitor 4 critical points: 2 rooftop unit return air temperatures, 1 chiller supply water temperature, and 1 boiler exhaust temperature. Each point uses a 4–20 mA RTD transmitter (powered by an external 24 VDC supply) wired to the Metso IOP304’s channels. The module’s Modbus RTU interface connects to a Siemens S7-1200 PLC, which displays temperatures on a simple HMI. When the chiller temperature exceeds 12 °C (triggering a 20 mA signal), the PLC sends an alert to facility staff via text. The Metso IOP304’s compact size fits in the building’s main HVAC panel (shared with 3 other small components), and its fixed configuration prevents accidental changes—ensuring consistent monitoring for 3+ years.
In small manufacturing, a furniture factory uses the Metso IOP304 to track 4 glue tank levels (one per production line). Each tank has a 4–20 mA ultrasonic level transmitter (wired to the module), and the Metso IOP304 sends data to an Allen-Bradley Micro820 PLC. The PLC stops the line if a tank level drops below 10% (5 mA signal), preventing glue shortages that cause defective furniture. The factory’s technician appreciates the Metso IOP304’s simplicity: no software is needed to verify operation—channel LEDs confirm each transmitter is sending data. The module’s low power consumption (1.2 W) aligns with the factory’s energy-saving goals, and its low cost allows the factory to add a second Metso IOP304 for monitoring paint viscosity in the future.
METSO IOP304
Related model recommendations
Metso IOP331: Digital input sibling of the Metso IOP304—8 channels, NPN/PNP auto-detect, auxiliary power—for users needing to add digital sensor monitoring (e.g., limit switches) alongside analog data.
Metso IOP320: Higher-tier analog output module—4–20 mA output, IP65, HART—for users scaling from monitoring to control (e.g., triggering valves or VFDs based on Metso IOP304 data).
Metso FieldCare Lite: Simplified software for the Metso IOP304—enables Modbus address setup, channel status checks, and basic data logging (no advanced diagnostics).
Metso External Sensor Power Supply (PS-241): 24 VDC, 1 A power supply for the Metso IOP304—powers 4–20 mA sensors (since the module lacks auxiliary output), ensuring consistent sensor performance.
Siemens S7-1200 PLC (1211C): Budget-friendly PLC fully compatible with the Metso IOP304—handles Modbus RTU communication and basic HMI integration for small monitoring systems.
Metso IOP306: 6-channel upgrade of the Metso IOP304—same simplicity, 2 extra channels—for users needing to monitor 5–6 analog points (e.g., 3 temperatures + 3 pressures).
Allen-Bradley Micro820 PLC: Compact PLC ideal for pairing with the Metso IOP304—supports Modbus RTU via built-in RS-485, suitable for food/beverage small lines.
Metso Terminal Block Cover (TC-20): Accessory for the Metso IOP304—plastic cover that protects terminal blocks from dust and accidental contact (critical for open-panel installations).
Installation, commissioning and maintenance instructions
Installation preparation
Before installing the Metso IOP304, power off the control system and wear ESD wristbands to prevent static damage to the module’s 12-bit ADC. Verify the module’s power supply (18–30 VDC) matches the panel’s external 24 VDC source—do not use 220 VAC (unlike the Metso IOP320). Mount the Metso IOP304 on a standard 35 mm DIN rail—ensure at least 5 mm of clearance on both sides (for airflow) and avoid installing near heat sources (e.g., relays).
Wiring requires a small flathead screwdriver (terminal blocks are non-removable): strip 5 mm of insulation from 24–18 AWG wire, insert into the terminal (labeled: V+, GND, CH1–CH4, A/B for RS-485), and tighten the screw to 0.2 N·m (avoid over-tightening). Connect sensors to CH1–CH4 (ensure 4–20 mA signal polarity: + to CHx+, – to GND). Connect the RS-485 A/B lines to the PLC’s Modbus port—use twisted-pair cable (min. 0.5 mm²) for runs up to 100 meters.
Commissioning and maintenance
Power on the system and verify the Metso IOP304’s power LED turns green (red = fault). Check each channel LED: if a sensor is connected and powered, the LED will turn green (no LED = wiring error or sensor fault). Use a multimeter to measure the sensor signal at the module’s terminals (e.g., 4 mA = 0% sensor range, 20 mA = 100%)—confirm it matches the expected value.
For configuration, install Metso FieldCare Lite on a PC, connect via RS-485 to USB adapter, and assign a unique Modbus address (1–247) to the Metso IOP304 (default: 1). No other settings are adjustable (factory-locked). For maintenance, inspect the module quarterly: wipe dust from the housing with a dry cloth, check terminal screws for tightness (loose wires cause intermittent signals), and verify the power supply voltage (24 VDC ±10%).
If a channel fails (LED off but sensor is powered), disconnect the sensor and test with a known-good 4–20 mA signal generator—if the LED turns green, replace the sensor; if not, replace the entire Metso IOP304 (no field-repairable parts). Store spare modules in a dry, room-temperature cabinet (avoid -10 °C below or +55 °C above).
Service and guarantee commitment
Metso provides a 1-year standard warranty for the Metso IOP304, covering defects in materials, workmanship, and performance (e.g., channel failure, communication issues). During the warranty period, Metso will replace the module free of charge if it fails under normal indoor use (proof of purchase required). No extended service plans are offered for the Metso IOP304—consistent with its entry-level positioning.
Metso’s technical support team offers basic assistance for the Metso IOP304—available via email (24-hour response time during business days) and online FAQs. Support includes help with Modbus address setup, wiring verification, and Metso FieldCare Lite troubleshooting. No phone support is provided (reserved for higher-tier modules like the Metso IOP320).
For out-of-warranty issues, Metso does not offer repairs—instead, it provides a 15% discount on a new Metso IOP304 (valid for 6 months after failure). Customers also gain free access to simplified resources: a 2-page installation guide, Modbus RTU wiring diagram, and Metso FieldCare Lite tutorial video. This commitment balances affordability with reliability, ensuring entry-level users receive the support they need without extra costs.
