Dickson Co., Addison, IL, offers the D250 (temperature and humidity) and D251 (temperature) wireless sensors that use a 900 MHz ISM frequency range. The sensors communicate with a receiver with USB cable and software connected to a central computer. The central computer then records and monitors the temperature/humidity from up to 200 remote sensors. Each sensor must be within 50–200 ft. from the receiver. Ranges are 0%–100% RH and –28°C to 48°C (D250) and –28°C to 48°C (D251).
