LTM8990 is a wireless temperature and humidity sensor, which can measure temperature and humidity. The measurement range is -10℃ - +60℃, 1% - 99% (non-condensation), with an accuracy of ±0.5℃ and ±3%RH. It uses 9600bps wireless transmission, with a power of 10mW and a frequency of 433MHz. The transmission distance can reach 300 meters.
This manual describes how to install and configure the LTM 8990 wireless temperature‑humidity sensor. It covers wiring, power supply, and mounting directions, as well as the communication settings required to connect the sensor to a host system.
The document also explains the data protocol, including temperature and humidity byte formats, checksum calculation, and example data frames. Technical specifications such as measurement range, accuracy, power consumption, and dimensions are listed for quick reference. This manual is written in Japanese.
| Temperature accuracy | ±0.5 °C |
|---|---|
| Humidity range | 1 % to 99 % RH |
| Humidity accuracy | ±3 % RH (25 °C) |
| Baud rate | 9600 bps (fixed) |
| Power supply | 9‑18 VDC, <2 W |
| Maximum RF output power | 10 mW |
| Operating frequency | 433 MHz |
| Dimensions | 100 × 80 × 30 mm |
| Lifetime | 10 000 hours (approx.) |
It communicates at a fixed 9600 bps.
Humidity is computed as (HH × 256 + HL) ÷ 2, where HH is the high‑byte and HL the low‑byte of the humidity data.
The device operates from 9 V to 18 V DC with a power consumption of less than 2 W.