Switching Device ROSSMA® IIOT-AMS Modbus Utility

The ROSSMA IIOT-AMS MODBUS Utility meter-switch is designed for automated data collection from utility metering devices via RS-485 interface with subsequent wireless transmission over LoRaWAN or NB-IoT networks.

The device is specially designed for housing and communal services (HCS) metering systems and commercial energy resource accounting.

Fig. ROSSMA IIOT-AMS MODBUS Utility meter-switch appearance

Compatible Metering Devices

Electricity Meters

• Mercury (230, 234, 236, 200)
• Energomera (CE102, CE301, CE303)
• Matrix (NP)
• Incotex (Mercury 201, 203, 206)
• ABB (A, B, C series)
• Schneider Electric (PM/EM series)
• Other meters with RS-485 interface and Modbus RTU protocol

Heat Calculators

• SPT (941, 942, 943, 961, 962, 963 series)
• VKT (7, 9)
• Pulsar (TK, TM)
• Vzlet (TSR, TSR-M, TSRV)
• Teplokom (MIR, TV7)
• KMCh (Heat meter)
• Other heat meters supporting Modbus RTU

Equipment is registered in the register of the Ministry of Industry and Trade of the Russian Federation as equipment manufactured on the territory of the Russian Federation (Conclusion 48859/11 dated June 11, 2021).

Technical Specifications

Connection Interfaces

• 1 serial interface: RS-485 (Modbus RTU)
• Discrete inputs: 3 multifunctional inputs (pulse counting or status monitoring)
• Built-in temperature sensor: yes (sent with each transmission)
• Power voltage measurement: yes (battery status monitoring)

Electrical Characteristics

• Supply voltage (mains): 230 V, 50 Hz
• Supply voltage (autonomous): 3.3-3.6 V (built-in battery)
• Power consumption (mains): 62.7 W
• Power consumption (autonomous): 0.99 W
• Current consumption (autonomous): 0.3 A

Operating Characteristics

• Operating temperature range: -55…+80°C
• Relative humidity: up to 95% at +25°C (non-condensing)
• Atmospheric pressure: 84...106.7 kPa
• Protection degree: IP65 (industrial), IP66 (explosion-proof)
• Explosion protection marking: 1Ex e IIC T4 Gb X

LoRaWAN Characteristics

• Device class: A or C
• Frequency plan: RU868, EU868, IN865, AS923, AU915, KR920, US915, KZ865
• Activation method: ABP or OTAA (configurable), default ABP
• Transmission interval: configurable via LoRaWAN (from 1 minute)
• Receiver sensitivity: -138 dBm
• Radio range: up to 5 km in urban areas; up to 15 km in rural areas
• Transmitter power: 25 mW (default), maximum 100 mW

NB-IoT Characteristics

• Frequency bands: B1/2/3/5/8/12/13/17/18/19/20/25/26/28/66/70
• Data rate: 25/20 kbps (single-tone) or 60 kbps (multi-tone) (DL/UL)
• Transmission interval: configurable
• Sensitivity: -138 dBm
• Radio range: up to 5 km in dense urban areas; up to 15 km outside populated areas

Design and Dimensions

• Housing dimensions (industrial): 115×90×50 mm
• Housing dimensions (explosion-proof): 260×160×90 mm, 220×120×90 mm, 80×75×55 mm
• Cable gland type: specified upon agreement with customer
• Mounting: DIN rail adapter or mounting loops

Capabilities

• Polling up to 8 metering devices on one RS-485 bus
• Automatic reading collection by schedule
• Data archiving in built-in non-volatile memory
• Wireless transmission via LoRaWAN/NB-IoT
• Remote configuration via network server
• 3 discrete inputs for connecting pulse outputs or contacts
• Built-in temperature sensor for operating conditions monitoring
• Communication quality control with meters (error diagnostics)
• Batch data transmission for traffic savings

Application Areas

Housing and Communal Services (HCS)

• Apartment buildings: automated reading collection from apartment meters
• Building-wide meters: monitoring electricity, heat, water consumption
• Elevator units: heating system monitoring
• Heat substations: heat supply parameter control

Commercial Energy Accounting

• Shopping and business centers: tenant energy consumption control
• Industrial facilities: workshop-level energy accounting
• Office buildings: utility cost distribution

Energy Supply Organizations

• Electric grid companies: remote electricity meter data collection
• Heat supply organizations: heat substations and subscriber monitoring
• Water utilities: water consumption control (with Modbus water meters)

Indication

The ROSSMA IIOT-AMS MODBUS Utility meter-switch has the following indicators:

• ACT — data exchange with meters via Modbus RTU protocol
• LoRa — data transmission/reception via LoRaWAN network
• NET — NB-IoT network connection
• Success — successful NB-IoT data transmission
• Err — Modbus protocol exchange error indicator
• PWR — device power present

The meter-switch has a RESET button for device restart and forced data transmission.

Connecting Metering Devices

RS-485 Connection Diagram

Bus connection topology:

┌─────────────────────┐
│ ROSSMA MODBUS       │
│ Utility             │
│                     │
│  A+  ───────┬───────── A+ (Meter 1: Mercury 230, ID=1)
│             │
│  B-  ───────┼────┬──── B- (Meter 1)
│             │    │
│  GND ───────┼────┼──── GND (Meter 1)
└─────────────┘    │
                   ├──── A+ (Meter 2: Energomera CE301, ID=2)
                   │
                   ├──── B- (Meter 2)
                   │
                   ├──── GND (Meter 2)
                   │
                   ├──── A+ (Heat calculator: SPT-941, ID=3)
                   │
                   ├──── B- (Heat calculator)
                   │
                   └──── GND (Heat calculator)

IMPORTANT: Maximum RS-485 bus length: 1200 meters. Use signal repeaters if exceeded.

Terminal Block Pinout

Cable Requirements

Recommended RS-485 cable:

• Shielded twisted pair (STP)
• Cross-section: 0.5-0.75 mm² (AWG 20-18)
• Characteristic impedance: 120 Ohm
• Shield grounded on one side (at switch)

Application Examples

Apartment Building Metering Automation

Task: Collecting readings from apartment electricity meters

Equipment:

• ROSSMA IIOT-AMS MODBUS Utility
• Mercury 230 electricity meters (Slave ID: 1-8)

Data for transmission:

• Active energy readings by tariffs (kWh)
• Phase voltage and current
• Grid frequency
• Error codes

Frequency: once per day (at 23:55)

Heat Substation Monitoring

Task: Individual heat substation (IHS) monitoring

Equipment:

• ROSSMA IIOT-AMS MODBUS Utility
• SPT-941 heat calculator (Slave ID: 1)
• Mercury 230 electricity meter (Slave ID: 2)

Data:

• Supply/return temperature (°C)
• Coolant flow rate (m³/h)
• Heat energy (Gcal)
• Pump drive electricity (kWh)
• Equipment status

Frequency: every 15 minutes

Additional Information

• Device Installation — installation instructions
• Battery Replacement — battery replacement
• Protocols and Commands — control commands and data formats
• ROSSMA Configurator — device configuration
• Troubleshooting — diagnostics and problem solving

Related Pages

Software:

• ROSSMA Configurator — Modbus profile settings for meters
• ROSSMA NETS Server — reading viewing, report generation
• Data Decoder — Modbus payload analysis

Technical Documentation:

• Exchange Protocols — MODBUS device packet format
• LoRaWAN Technology — RU864 frequency plan, device classes
• Quick Start — first network connection

Other Devices:

• MODBUS — for industrial controllers
• ANALOG Single Channel — for 4-20 mA sensors
• PULSE — for pulse sensors
• Device Catalog — all ROSSMA IIoT-AMS models