Telemetry transmitter WTU

Overview
The WTU (Wireless Transmission Unit) replaces wired Modbus RTU connections with a secure wireless link designed for industrial and compressed-air networks where cabling is impractical or costly. It provides plug-and-play connectivity between Modbus masters, slaves, sensors, data loggers and gateways, supporting long-distance links and multi-point topologies while ensuring encrypted data transfer.

Key features

• Long-distance wireless communication in ISM bands (region-specific frequencies)
• Stationary (WTU-S) and portable (WTU-P) versions; battery-powered portable option for mobile setups
• Modbus RTU (RS485) protocol support
• AES 128-bit encryption for secure transmission
• Transparent data transmission to preserve Modbus framing
• Scalable multi-point monitoring (multiple sensors per WTU slave)
• Repeater mode to extend wireless range
• Quick configuration with the S4C-WTU mobile app (guided setup and signal tests)
• Flexible roles: Master, Slave or Repeater
• Up to 16 slave devices per master

Available models

• WTU-S — stationary version for fixed installations
• WTU-P — portable version with integrated battery for mobile measurements
• WTU-PM — portable master version for handheld master devices

Applications

• Distributed compressed-air networks: connect sensors in remote or hard-to-wire locations
• Industrial sites: bridge Modbus links between buildings or production areas
• Mobile measurement setups: wireless data from portable instruments
• Retrofitting existing installations to avoid cable routing and downtime
• Range extension or interference mitigation using repeater mode

Technical specifications

• GENERAL DATA:
  Wireless frequency: 470-510 MHz (CN470); 863-870 MHz (EU868); 915-928 MHz (US915)
• GENERAL DATA:
  Housing material: Plastic casing
• GENERAL DATA:
  Protection class: IP65
• GENERAL DATA:
  LED indicator: 1 x LED
• GENERAL DATA:
  Operating temperature: 0 ~ 50 °C
• GENERAL DATA:
  Humidity: <90% RH, no condensation
• GENERAL DATA:
  Dimensions: WTU-S & WTU-PM: 80 x 60 x 30.3 mm; WTU-P: 130 x 90 x 40 mm
• GENERAL DATA:
  Weight: WTU-S & WTU-PM: 120 g; WTU-P: 470 g
• ELECTRICAL DATA:
  Power input: WTU-S & WTU-PM: 18...28 VDC / 0.5 A; WTU-P: 18...28 VDC / 1 A
• ELECTRICAL DATA:
  Power output: WTU-S & WTU-PM: 18...28 VDC / 0.5 A; WTU-P: 24 VDC / 0.5 A
• ELECTRICAL DATA:
  Power consumption: WTU-S & WTU-PM: <= 0.3 W; WTU-P: <= 0.5 W
• ELECTRICAL DATA:
  Battery (WTU-P): Lithium‑ion 3500 mAh, 11.1 V
• INTERFACE:
  LED status: Constant green = Power on; Green blinking = Receiving data; Constant red = Error; Red blinking = Transmitting data
• INTERFACE:
  Status screen (WTU-P): Battery level display
• INTERFACE:
  Connector: RS485 (Modbus/RTU)
• INTERFACE:
  Transmission: Transparent data transmission
• INTERFACE:
  Encryption: AES 128-bit