Wireless sensing system for Temperature and Humidity

The wireless sensing system consists of sensor units and a base station. The sensors measure input values like temperature, humidity and process signals and transmit the measured data over a secure wireless link to the base station. Measurement and transmission intervals can be set by means of software on a PC. This software - called SensorGraph - is part of WiSensys® and is used during installation.

The sensor can locally store up to 10.000 measurements in non-volatile memory. This storage is used when a connection to the base station is not available to ensure that measurements are not lost. Whenever the sensor and base station are in range again, the data is transmitted to the base station. Overwrites oldest data when full.

Trip values can be set in each sensor for monitoring alarm conditions. The sensor is powered with a battery with an average battery lifetime of 3 years.

The WiSensys® base station receives sensing data from all sensors and automatically trans-fers these values to a PC, if connected. The base station can optionally store 100.000 measurement values. This storage can be used for logging values when a PC or data logger is not connected. The base station has an RS232 DTE interface and can optionally be enhanced with other digital and analog outputs like RS485, 0-20mA and 0-10V. A switched relay can be made available for e.g. connecting an external alarm indication to the base station.

Upon installation, the WiSensys® SensorGraph software is used to install the system. Friendly names can be assigned to each sensor. Measurement and transmission intervals can be specified and trip values can be set. These values can be changed later when needed.

The coverage of the system is determined by the distance between the WiSensys® base station and the sensors. If the coverage area of 1 base station is not enough, up to 2 additional base stations can be added to increase the coverage area. All base stations can be networked to be able to collect all measurement data on 1 location.

Available sensors

WS-DLTi - internal temperature sensor

WS-DLTa-p100 - external Pt100 temperature sensor

WS-DLTa-p1000 - external Pt1000 temperature sensor

WS-DLTc - internal relative humidity and temperature sensor

WS-DLXa - analog sensor for process signals

WS-DLXv - analog sensor for process signals

WS-DLXc - digital sensor for switch contact signals (open/close)

Measurement range

-20°C to +80°C with WS-DLTi and WS-DLTc

-50°C to +200°C with WS-DLTa-p100 and WS-DLTa-p1000

10% to 95%RH with WS-DLTc (non-condensing)

4-20mA with WS-DLXa

0-30V DC with WS-DLXv

Measurement interval: from 1-200 seconds, programmable from PC

Transmission interval: from 1-10 samples, programmable from PC

Radio standard: ETS 300 220

Radio frequency: 868MHz (Europe), 915MHz (US)

Range: 1000m with free line-of-sight

WiSensys® maximum size: 3 base stations, 100 sensors

Easy to add sensors to operational system

PC software for installation, data logging and data presentation