Autonomous Switching Device ROSSMA® IIOT-AMS 1-Wire Ex (Temperature Sensor)

The autonomous ROSSMA IIOT-AMS 1-Wire Ex switch with 1-Wire digital temperature sensor is designed for temperature measurement with subsequent wireless data transmission. The device is developed for use in hazardous areas at industrial facilities, utilities, and hard-to-reach locations. The switch enables installation of measuring instruments in places without power sources and operates in harsh climatic and weather conditions.

Fig. ROSSMA IIOT-AMS 1-WIRE Ex meter-switch appearance

Compatible sensors:

• Temperature sensors with 1-Wire digital interface (DS18B20, DS18S20 and analogs)

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 interface: 1-Wire (Dallas Semiconductor digital protocol)
• Number of inputs: 1 digital 1-Wire input
• Battery type: 14 A/h; 126 A/h; 168 A/h
• Transmission interval/14 A/h battery life: 1 min/90 days, 2 min/180 days, 10 min/300 days, 1 hour/3 years 150 days, 24 hours/10 years
• Operating temperature range: -55…+85°C
• Built-in temperature sensor: no (external 1-Wire sensors used)
• LoRaWAN device class: A
• LoRaWAN activation: OTAA/ABP (configurable), ABP — default
• Antenna type: internal
• Transmitter power: 25 mW (configurable)
• Receiver sensitivity: -138 dBm
• Supply voltage: built-in 3.6 V battery, 14 A/h capacity, D size
• Battery voltage measurement: yes (sent with each transmission)
• Housing dimensions: 75×70×55 mm
• Mounting: directly to sensor, cable ties to support, DIN rail, wall mount
• Radio range: up to 5 km in urban areas; up to 15 km in rural areas

Capabilities

• 1 digital 1-Wire input for temperature sensor connection
• Configurable measurement interval from 1 time/min
• On-demand measurement by command
• Cascade connection of multiple sensors on one bus (up to 10 devices)
• Automatic sensor identification by unique ROM code
• High measurement accuracy (±0.5°C for DS18B20)

Functional Features

The meter-switch is a Class A device (LoRaWAN® classification) providing the following functionality:

Network capabilities:

• ADR support (Adaptive Data Rate) — automatic data rate adaptation
• Configurable activation type: OTAA / ABP (default: ABP)
• Frequency plan: EU-868 / RU-868 (default: RU-868)
• Confirmed packet transmission support (configurable)

Operating parameters:

• Transmission interval: from 1 min and above (remotely configurable via LoRaWAN®)
• Default value: 1 time per hour
• Number of inputs: 1 (one 1-Wire digital input)
• Battery capacity: 14000 mAh — designed for 40,000 data packets ± 10%

Recommendation: Do not set intervals less than 1 minute to ensure long autonomous operation.

1-Wire Protocol

1-Wire (One-Wire) — a serial communication protocol developed by Dallas Semiconductor (now Maxim Integrated). Protocol features:

1-Wire advantages:

• Only 2 wires: data + ground (power can be supplied via data line)
• Each sensor has a unique 64-bit ROM code
• Multiple devices can be connected to one bus
• Range up to 100 meters with proper topology
• Low power consumption

Supported sensors:

• DS18B20 — digital temperature sensor (-55°C...+125°C, accuracy ±0.5°C)
• DS18S20 — DS18B20 predecessor (9-bit resolution)
• DS1822 — DS18B20 analog with simplified functionality

Contacts and Connection

Switch Contact Description

ROSSMA IIOT-AMS 1-WIRE Ex has the following contacts for sensor connection:

Maximum parameters:

• Sensor power voltage: 3.3V
• Maximum VCC current: 50 mA
• Number of sensors on bus: up to 10
• DQ line length: up to 100 meters

IMPORTANT: Use a 4.7 kOhm pull-up resistor between DQ and VCC when connecting multiple sensors or when line length exceeds 10 meters.

Connecting 1-Wire Sensors

Connection Diagram

Single sensor connection topology:

┌─────────────────┐
│ ROSSMA 1-WIRE   │
│                 │
│  DQ  ──────────────── DQ (Data) — DS18B20
│                 │
│  GND ──────────────── GND (Ground) — DS18B20
│                 │
│  VCC ──────────────── VDD (Power) — DS18B20
└─────────────────┘

Multiple sensor connection topology:

┌─────────────────┐
│ ROSSMA 1-WIRE   │
│                 │
│  DQ  ────┬───────── DQ (sensor 1)
│          │
│          ├───────── DQ (sensor 2)
│          │
│          └───────── DQ (sensor 3)
│                 │
│  GND ────┬───────── GND (all sensors)
│                 │
│  VCC ────┬───────── VDD (all sensors)
└─────────────────┘

IMPORTANT: When connecting multiple sensors, a 4.7 kOhm pull-up resistor between DQ and VCC is required.

DS18B20 Sensor Pinout

Standard TO-92 package (bottom view, pins facing you):

  ___
 /   
|  O  |  — top view
 ___/
  | | |
  1 2 3

1 — GND (ground, black)
2 — DQ (data, yellow)
3 — VDD (power +3.3V, red)

Cable Requirements

Recommended cable:

• Twisted pair (UTP Cat5 or higher)
• Shielded cable for industrial conditions
• Maximum line length: 100 meters (at 15.4 kbps)
• Cross-section: 0.5-0.75 mm²

Application Examples

Temperature Monitoring in Refrigeration Chambers

Task: Temperature control in freezer chambers at warehouse

Equipment:

• ROSSMA IIOT-AMS 1-WIRE Ex
• DS18B20 sensor in sealed housing

Data for transmission:

• Chamber temperature (°C)
• Battery charge
• Communication status

Frequency: every 10 minutes

Pipeline Temperature Control

Task: Temperature monitoring on oil/gas pipeline

Equipment:

• ROSSMA IIOT-AMS 1-WIRE Ex
• 5× DS18B20 sensors at different pipeline sections

Data:

• Temperature at 5 points
• Anomaly detection
• Freezing warning

Transformer Substation Temperature Monitoring

Task: Power transformer temperature control

Equipment:

• ROSSMA IIOT-AMS 1-WIRE Ex
• 3× DS18B20 sensors (top, middle, bottom of transformer)

Data:

• Winding temperature
• Oil temperature
• Transformer overheating

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 — transmission interval settings, sensor identification
• ROSSMA NETS Server — telemetry viewing, device management
• Data Decoder — 1-WIRE device payload analysis

Technical Documentation:

• Exchange Protocols — 1-WIRE device packet format
• LoRaWAN Technology — RU864 frequency plan, device classes
• Quick Start — first network connection
• Battery Life Calculator — battery life calculation

Other Devices:

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