Modbus Outdoor Probe LKM459
LKM459 Outdoor Temperature / Humidity Probe Modbus RTU
The LKM459 is an industrial-grade outdoor temperature and humidity probe with Modbus RTU (RS-485), designed for use in building automation, industrial plants, and control cabinet installation. The device measures temperature and relative humidity with a resolution of 0.1 (°C / % RH) and is factory calibrated. Minor field corrections can be made using two mechanical adjustment controls.
Technical and functional highlights:
- Communication: Modbus RTU (RS-485), designed as slave. Write access can only be activated with jumper JP1 set.
- Parameterization: Mini USB for configuration (e.g., slave ID, baud rate) and for optional power supply.
- Integration:
- Easy connection to controllers
- Modbus TCP/IP possible via external gateway - The device is delivered fully calibrated and can be adjusted on site via P1 (temperature) and P2 (humidity).
- The mechanics feature a weather-resistant sintered cap, compact dimensions, and an easy-to-install housing.
- Areas of application: Outdoor measurement (weather protection recommended), HVAC systems, building management systems, and machine and plant monitoring.
| Feature | Value | Remark |
|---|---|---|
| Sensor | SHT31 semiconductor sensor | Integrated |
| Measuring principle | Capacitive / CMOS humidity sensor | |
| Measured quantities | Temperature, relative humidity | Optional pressure (depending on sensor) |
| Temperature range | -40 – +85 °C | |
| Humidity range | 0 – 100 % RH | |
| Temperature resolution | 0.1 °C | |
| Humidity resolution | 0.1 % RH | |
| Temperature accuracy | ±0.3 K (at 25 °C) | |
| Humidity accuracy | ±2 % RH (at 20 – 80 % RH) | |
| Response times (τ63%) | Temperature < 2 s; Humidity ≈ 8 s | |
| Long-term drift (temperature) | ≤ 0.03 K / year | Recommended, check |
| Long-term drift (humidity) | ≤ 0.25 % RH / year | Recommended, check |
| Supply voltage | 10 – 35 V DC via terminals | Alternative: via USB interface (5 V DC) |
| Power consumption | 10 mA at 24 V DC / 240 mW | |
| Reverse polarity protection | Yes | |
| Interface | RS485 (Modbus RTU) via terminals | Additionally Mini-USB Type B |
| Modbus default settings | Baud 19200, 8N1, Slave ID 1 | |
| Baud rates | 1200 / 2400 / 4800 / 9600 / 19200 | Software configurable |
| Max. RS485 cable length | Up to 1200 m | Dependent on topology and baud rate |
| Parity | Even / Odd / None | Software configurable |
| Stop bits | 1 or 2 | Software configurable |
| Termination resistor | None / 120 Ω | Software configurable |
| Operating environment | -40 – +85 °C; <95 % RH | |
| Connections | Screw terminals | 0.13 – 1.5 mm2 |
| Housing dimensions | 58 x 65 x 35 mm (W x D x H) | |
| Probe tube dimensions | Length: 45 mm; Diameter: 14 mm | |
| Weight | approx. 100 g | |
| Housing material | PA (polyamide) | Glass-fibre reinforced |
| Probe tube material | Steel | Sintered cap Teflon |
| Mounting | Wall | |
| Ingress protection | IP64 according to DIN EN 60529 | |
| Cable gland | PG9 screw connection | Recommended Ø 4 – 8 mm |
| EMC | EN 61326-1; EN 61326-2-3 | Emission and immunity |
| Conformity | CE, UKCA, RoHS |
Documents
| Document | Format | Language(s) |
|---|---|---|
| Datasheet – LKM459 Technical Specification |
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| Operating Instructions – LKM459 Installation and operating manual |
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Software
| Program / Package | Format | Language(s) |
|---|---|---|
| Service Program – LKM459 for Windows-PCs Parameterization Software |
ZIP | |
| Driver (ftdichip.com) USB driver |
Web | |