# AGRINOVO-RLM-120: 76 to 81 GHz FMCW Radar Level Meter

Agrinovo technical datasheet, revision 1.2 (October 2026).
PDF version: https://agrinovo.io/datasheets/sensors/AGRINOVO-RLM-120_Datasheet.pdf

## 1. Overview

The AGRINOVO-RLM-120 is a frequency modulated continuous wave (FMCW) radar level meter operating at 76 to 81 GHz. Its high operating frequency and short wavelength make it particularly suitable for both liquid and solid level measurement applications, with a maximum range of up to 120 m.

### Key Features

- 76 to 81 GHz FMCW technology
- Up to 120 m measuring range
- Accuracy: ±1 mm
- 3° / 8° beam angle
- HART and Modbus communication
- 4-20 mA / RS485 output
- Bluetooth configuration via mobile
- IP67, Ex d ia IIC T6

### Applications

- Liquid level measurement in tanks and vessels
- Solid/powder level measurement in silos
- High-temperature and high-pressure process environments
- Chemical, petrochemical, and food industry

## 2. Specifications

| Parameter | Specification |
|:----------|:--------------|
| **Frequency Range** | 76 to 81 GHz |
| **Measuring Range** | 15 m / 35 m / 85 m / 120 m |
| **Accuracy** | ±1 mm |
| **Beam Angle** | 3°, 8° |
| **Power Supply** | 12 to 24 VDC |
| **Output Signal** | 4-20 mA, RS485 |
| **Communication** | HART, Modbus |
| **Fault Output** | No change, 22 mA, 3.6 mA |
| **Process Temperature** | -30\~80°C / -30\~200°C / -30\~1000°C |
| **Process Pressure** | -0.1\~1.8 MPa |
| **Operating Temp (Display)** | -20\~70°C |
| **Measurement Interval** | 0.3 s minimum |
| **Max Power Consumption** | 2-wire: 20 mA / 4-wire: 70 mA |
| **Shell Material** | Aluminum shell, stainless steel |
| **Cable Entry** | M20x1.5 |
| **Antenna Type** | Lens antenna |
| **Blind Area** | 0.08 to 0.5 cm |
| **Protection Level** | IP67 |
| **Explosion-Proof Grade** | Ex d ia IIC T6 |
| **Connection Method** | Thread, universal flange, anti-corrosion, high-temp/pressure |
| **Humidity** | < 95% |

## 3. Installation

### Position Selection

When measuring liquids, align the meter vertically with the medium surface for optimal measurement.

Install the instrument at least 200 mm away from the vessel wall.

Position the antenna away from the feed inlet to obtain the best measurement results. If the tank wall is not smooth (corrugated steel, welds, joints, etc.), install the device as far away from the tank wall as possible. If necessary, use the antenna angle adjustment device to avoid interfering reflections.

## 4. Dimensions

### Threaded Connection

G1-1/2 thread (34 mm antenna)

G3-1/2 thread (70 mm antenna)

### Flange Connection

**Anti-corrosion flange (PN16)**

| Size | A (mm) | B (mm) | C (mm) | H (mm) | N (bolts) |
|:-----|:-------|:-------|:-------|:-------|:----------|
| DN80 | 160 | 200 | 17.5 | 20 | 8 |
| DN100 | 180 | 220 | 17.5 | 20 | 8 |

Normal temperature

High temperature (-30\~200°C)

**Small anti-corrosion flange (PN16)**

| Size | A (mm) | B (mm) | C (mm) | H (mm) | N (bolts) |
|:-----|:-------|:-------|:-------|:-------|:----------|
| DN50 | 125 | 165 | 17.5 | 20 | 4 |
| DN65 | 145 | 185 | 18 | 20 | 4 |

**Universal flange (PN16)**

| Size | A (mm) | B (mm) | C (mm) | H (mm) | N (bolts) |
|:-----|:-------|:-------|:-------|:-------|:----------|
| DN80 | 160 | 200 | 17.5 | 20 | 8 |
| DN100 | 180 | 220 | 17.5 | 20 | 8 |

### Aluminum Shell

Shell dimensions: 152 mm height, 53 mm / 88 mm diameter

## 5. Electrical Connections

### 5.1 4-20 mA Two-Wire

### 5.2 4-20 mA Four-Wire

### 5.3 RS485 Four-Wire

### 5.4 Dual-Chamber 220V AC (4-20 mA Four-Wire)

In four-wire applications, when 4-20 mA is not output, terminals 3 to 4 are shorted.

## 6. RS485 Modbus Communication (RS485 Version)

### Communication Settings

| Parameter | Value |
|:----------|:------|
| **Protocol** | Modbus-RTU |
| **Baud Rate** | 9600 bps (default) |
| **Data Bits** | 8 |
| **Parity** | None |
| **Stop Bits** | 1 |
| **Default Address** | 0x01 |
| **Frame Interval Timeout** | 50 ms |
| **Byte Order** | CDAB (little-endian word swap) |

### Modbus Functions

- **0x03**  -  Read holding registers
- **0x10**  -  Write multiple registers

### Register Map

All registers use base address 0x20 (decimal 32). Parameters occupying 2 registers use UINT32 format; parameters occupying 1 register use UINT16 format.

**Measurement Registers (Function 0x03)**

| Address | Registers | Description | Unit |
|:--------|:----------|:------------|:-----|
| 0x0000 | 2 | Distance (empty height) | mm |
| 0x0002 | 2 | Level | mm |
| 0x0004 | 1 | Scale (ratio) | - |

**Basic Settings (Read 0x03 / Write 0x10)**

| Address | Reg | Description | Range |
|:--------|:----|:------------|:------|
| 0x0020 | 2 | Low calibration | 100 to 35000 / 100 to 85000 / 100 to 120000 mm |
| 0x0022 | 2 | High calibration | 0 to 35000 / 0 to 85000 / 0 to 120000 mm |
| 0x0024 | 2 | Range | 100 to 35000 / 100 to 85000 / 100 to 120000 mm |
| 0x0026 | 2 | Blind zone | 0 to 120000 mm |
| 0x0028 | 1 | Damping time | 0 to 60000 |
| 0x0029 | 1 | Media type | 0 = Liquid, 1 = Solid |
| 0x002A | 1 | Medium parameters | 0 = >10, 1 = 3 to 10, 2 = <3 |
| 0x002B | 1 | Application scenario | 0 to 4 (see table below) |

**Display Settings**

| Address | Reg | Description | Range |
|:--------|:----|:------------|:------|
| 0x002C | 1 | Measurement mode | 0 = Level, 1 = Distance, 2 = Scale |
| 0x002D | 1 | Distance unit | 0 = m, 1 = cm, 2 = mm |
| 0x002E | 1 | Language | 0 = Chinese, 1 = English |
| 0x002F | 1 | LCD contrast | 40 to 100 |

**Advanced Settings**

| Address | Reg | Description | Range |
|:--------|:----|:------------|:------|
| 0x0030 | 2 | False echo start | 0 to 85000 mm |
| 0x0032 | 2 | False echo end | 0 to 85000 mm |
| 0x0034 | 2 | False echo intensity | 0 to 200 |
| 0x0036 | 1 | Distance offset | -10000 to 10000 mm |
| 0x0037 | 1 | HART address | 0 to 32 |
| 0x0038 | 1 | Modbus address | 1 to 127 |
| 0x0039 | 1 | Modbus baud rate | 0 = 9600, 1 = 38400, 2 = 115200 |
| 0x003A | 1 | Output setting | 0 = 4-20 mA, 1 = 20-4 mA |
| 0x003B | 1 | Current simulation | 4000 to 20000 (÷1000 = mA) |
| 0x003C | 1 | Current function | 0 = No change, 1 = 22 mA, 2 = 3.6 mA |

### Reading Measurement Data

All measurement values use **CDAB byte order** (little-endian word swap).

**Read distance (empty height) in mm:**

```
Request:  01 03 00 00 00 02 C4 0B
Response: 01 03 04 [XX XX] [XX XX] [CRC]
```

**Read level in mm:**

```
Request:  01 03 00 02 00 02 65 CB
Response: 01 03 04 [XX XX] [XX XX] [CRC]
```

**Read scale (ratio):**

```
Request:  01 03 00 04 00 01 C5 CB
Response: 01 03 02 [XX XX] [CRC]
```

### Writing Configuration Example

**Write low calibration to 35000 mm (byte order CDAB):**

```
Request:  01 10 00 20 00 02 04 88 B8 00 00 5A 32
Response: 01 10 00 20 00 02 40 02
```

**Decoding CDAB byte order:** Data bytes `88 B8 00 00` are read as CDAB → value `0x000088B8` = 35000 mm.

## 7. Safety and Protection

### Safety Instructions

- Comply with local health and safety regulations
- All electrical work must be performed by trained professionals
- Check the instrument nameplate to verify product specifications
- Ensure supply voltage matches the instrument's nameplate requirements

### IP67 Protection

**To ensure IP67 compliance:**

- Ensure the sealing head is not damaged
- Ensure the cable is not damaged
- Use cable that meets electrical connection specifications
- Bend the cable downward before entering the electrical interface to prevent water ingress (1)
- Tighten the cable sealing head (2)
- Plug unused electrical interfaces with a blind plug (3)

## 8. Instrument Operation

### Button Description

| Button | Function |
|:-------|:---------|
| **BK** | Exit programming mode / Return to previous menu / Switch to echo interface |
| **Up** | Modify instrument parameters / View instrument information |
| **Cycle** | Switch instrument interface / Select menu item / Select edit position |
| **OK** | Enter edit mode / Confirm parameter modification |

### Main Interface

- **6.747**: Real-time measurement value
- **L**: Measurement mode  -  Level (L), Distance/empty height (H), Ratio (%)
- **H**: Communication method  -  HART (H), Modbus (R)
- **M**: Measurement unit
- **19.68°C**: Internal circuit temperature
- **Warning icon**: Fault code prompt (press Up key to view details)
- **Square indicator**: Communication status (flashing every 1 s = normal)

### Echo Interface

Press BK on the main interface to enter the echo display.

- **260 dB**: Echo strength
- **3.253 m**: Echo position
- **Black arrow**: Real-time measured distance
- **16.00**: Range setting value

### Menu Structure

Press OK on the main interface to enter the menu.

Basic settings page

Advanced settings page

| Menu | Contents |
|:-----|:---------|
| **Basic Settings** | Low/high calibration, range, blind zone, damping time, media type, medium parameters, application scenarios |
| **Display** | Measurement mode, distance unit, language, LCD contrast |
| **Advanced Settings** | False echo learning, distance offset, bus address, output mode, current simulation, current function |
| **Service** | Echo index, echo ratio, window settings, echo lock, primary/secondary filter, response rate, threshold setting |
| **Factory Settings** | Factory reset |

## 9. Configuration Guide

### Basic Settings

**Low/High Calibration:** The low position corresponds to the empty level, and the high position corresponds to the full level. For example, for a 10 m tank: set high position to 0 m and low position to 10 m.

**Range:** Set the range at least 2 m larger than the actual tank height so the instrument can obtain a complete echo. The range determines the echo processing window  -  echoes outside the range are ignored.

**Blind Zone:** Use the blind zone setting when a fixed obstacle near the sensor surface interferes with measurement and the maximum material level does not reach the obstacle.

**Damping Time:** Smooths sudden changes in measurement results to more accurately reflect the average material level position.

**Media Type:** Select Liquid or Solid. This automatically adjusts the application and medium parameter menus.

**Medium Parameters:**

| Solid | Liquid |
|:------|:-------|
| Chunk | Dielectric constant > 10 |
| Nub | Dielectric constant 3 to 10 |
| Dust | Dielectric constant < 3 |

**Application Scenarios:**

| Solid | Liquid |
|:------|:-------|
| Narrow and high type | Small container  -  fast response |
| Large capacity | Medium container  -  most conditions |
| Crusher | Large container  -  smooth output |
| Stockpile | Stirring  -  agitator applications |
| Demo | Demo |

### Display Settings

- **Measurement Mode:** Level, Distance (empty height), or Scale (ratio)
- **Distance Units:** m, cm, mm, ft, in (default: m)
- **Language:** Chinese, English, Korean, Russian
- **LCD Contrast:** 0 to 100 (higher = darker)

### Advanced Settings

**False Echo Learning:** Shields interference echoes from obstacles inside the container. Set the start point, end point, and intensity to form a threshold curve.

**Distance Offset:** Corrects deviation between measured and actual values. Factory-calibrated by default.

**Bus Address:**

| Protocol | Range | Notes |
|:---------|:------|:------|
| HART | 0 to 32 | When address differs from 0, current is fixed at 4 mA |
| Modbus | 1 to 127 | - |

**Output Mode:** Select 4-20 mA or 20-4 mA output direction.

**Current Simulation:** Outputs a specific current value to verify the 4-20 mA loop accuracy. Exit to resume normal operation.

**Current Function:** Sets the output current value when a signal loss fault occurs (NULL, 22 mA, or 3.6 mA).

### Service Settings

- **Echo Index:** Adjusts waveform change speed (higher = more stable)
- **Echo Ratio:** Percentage of echo outside the window being greater than the echo inside the window
- **Window Settings:** Search range before/after waveform is locked; timer controls arrow tracking speed
- **Echo Lock:** Lock to search within window range only; unlock to search the full range
- **Primary/Secondary Filtering:** Enable/disable based on measurement environment (enabled by default)
- **Response Rate:** Adjusts response rate to actual material level changes
- **Threshold Setting:** Higher threshold requires stronger effective echo amplitude, helping eliminate small signal clutter

## 10. Fault Codes

| Code | Hex | Description |
|:-----|:----|:------------|
| 1 | 0x0000 | Normal operation |
| 2 | 0x0001 | Echo lost |
| 3 | 0x0002 | ADC or TR failure |
| 4 | 0x0004 | 4-20 mA alarm |
| 5 | 0x0008 | Temperature sensor fault |
| 6 | 0x0010 | File system alarm |

Combined codes indicate multiple simultaneous faults (e.g., 0x0003 = echo lost + ADC/TR failure).

## 11. Communication and Debugging

The instrument can be configured on-site via the LCD panel or remotely through a PC. Communication methods:

- USB to TTL serial line (two-wire system)
- USB to RS485 serial line (four-wire system)
- USB to HART (two-wire system)
- Bluetooth via mobile phone

### Menu Tree

## Ordering Information

| Part number | Description |
|:------------|:------------|
| AGRINOVO-RLM-120 | 76 to 81 GHz FMCW Radar Level Meter |

## Revision History

| Rev | Date | Changes |
|:----|:-----|:--------|
| 1.0 | June 2026 | Initial release |
| 1.1 | August 2026 | Layout revision |
| 1.2 | October 2026 | New layout; corrected Modbus example CRC values |

## Contact

Agrinovo, https://agrinovo.io/products, contact@agrinovo.io, +972 54 688 8148 (direct / WhatsApp).
Specifications subject to change without notice.