NTC Web Thermometer: Professional Temperature Monitoring for IT and Industry
In times of increasing digitalization and growing demands on IT infrastructure, precise monitoring of ambient temperatures is becoming ever more important. The Web-Thermometer NTC from Wiesemann & Theis offers a professional solution for network-based temperature measurement in server rooms, data centers, network cabinets, and industrial applications. With its integrated NTC sensor, comprehensive network protocols, and powerful data logger, this device sets new standards in building and IT monitoring.
The NTC temperature sensor of the Web-Thermometer continuously captures temperatures from minus 45 degrees Celsius to plus 75 degrees Celsius, covering all common requirements for room temperature monitoring. Measurements are recorded with a resolution of one-tenth of a degree Celsius and are immediately available via the integrated web interface or modern network protocols such as MQTT, REST-API, OPC UA, and Modbus-TCP. Thanks to Power-over-Ethernet, the device requires no separate power supply and can be particularly easily integrated into existing network infrastructures.
Particularly noteworthy is the integrated data logger, which can store temperature trends for between 16 weeks and 20 years depending on the configured storage frequency. The battery-buffered real-time clock ensures correct timestamps even during power outages, which are automatically synchronized via NTP protocol. This long-term documentation is not only important for compliance requirements but also enables retrospective analysis of temperature developments and optimization of climate control in terms of Green IT and energy efficiency.
The flexibility of the Web-Thermometer NTC is evident in its diverse alarm options. Up to twelve individually configurable alarms can automatically send emails, trigger SNMP traps, generate Syslog messages, or publish MQTT messages when thresholds are exceeded. Freely definable thresholds, hysteresis, and delay times prevent false alarms while ensuring rapid responses to critical temperature fluctuations. These alarm functions make the device the ideal solution for all applications requiring uninterrupted temperature monitoring with automatic notifications.
Technical Features and NTC Sensor Performance
The heart of the Web-Thermometer is the high-quality NTC sensor with a resistance of 10 kiloohms. This sensor is specifically designed for typical climate ranges and offers excellent accuracy of plus minus 0.3 degrees Celsius with a relative error of plus minus 5.1 percent. The sensor is permanently connected to the device via a DB9 socket and features a one-meter connection cable. Unlike the PT100 or PT1000 variants, the sensor cable of the NTC model cannot be extended, which must be considered during installation planning.
The measurement frequency is four seconds, reliably capturing rapid temperature changes. However, the storage frequency can be individually set between 15 seconds, 30 seconds, one minute, five minutes, 15 minutes, or 60 minutes. This flexibility allows optimal adaptation to different monitoring scenarios: while tight measurement intervals are useful in critical areas like server rooms, larger storage intervals suffice in less temperature-critical environments to optimally utilize storage capacity.
Network Connection and Power-over-Ethernet
The Web-Thermometer NTC features an IEEE 802.3 compatible 10/100BaseT network port with Auto-MDIX function on a shielded RJ45 connector. This allows direct connection to switches or hubs using a standard patch cable without worrying about specific cable wiring. The galvanic isolation of the network port with 1500 volts provides additional safety and interference immunity.
Particularly practical is the support for Power-over-Ethernet according to IEEE 802.3af. The device belongs to PoE power class 1 with a power consumption between 0.44 and 3.84 watts. This enables complete power supply via the network cable, significantly simplifying installation. Both phantom power supply over the data lines and power supply over the unused wire pairs four, five, seven, and eight are supported. Alternatively, the device can be operated via an external DC power supply between 12 and 48 volts with a tolerance of plus minus ten percent. The connection is made via a pluggable screw terminal with reverse polarity protection.
Industry 4.0 and IoT Integration
MQTT protocol for direct connection to cloud platforms and IoT environments with publish-subscribe mechanism
REST-API for easy integration into web applications and modern software architectures with GET and POST methods
OPC UA as standard protocol in industrial automation with historizing function for time series
Modbus-TCP for connection to PLC systems and SCADA solutions via standardized registers
SNMP in versions v1, v2c, and v3 for integration into network management systems
Socket-API for TCP and UDP-based direct queries via configurable ports
FTP client for automatic file transfer and archiving of measurement values
HTTP and HTTPS for browser-based configuration and visualization with responsive design
Syslog for centralized logging of events and alarms
RSS feed for providing measurement values and status updates
Alarm Management and Notification System
The alarm management of the Web-Thermometer allows configuration of up to twelve independent alarms with different triggers and actions. Each alarm can be individually named, enabled or disabled, and equipped with specific conditions. Threshold exceedances serve as triggers, with both upper and lower limits definable. Hysteresis settings dampen fluctuations around critical thresholds and prevent unnecessary multiple notifications.
The actions upon alarm triggering are diverse:
Email dispatch with configurable subject and message text including current measurement values
SNMP traps to one or more network management systems
Syslog messages for central log servers
MQTT publish for IoT platforms and cloud services
HTTP requests for triggering actions on other systems
TCP and UDP messages to defined IP addresses and ports
Particularly flexible are the placeholders that can be used in alarm texts. Tags like T1 for current temperature, Z for date and time, or DN for device name allow messages to be dynamically enriched with current information. This facilitates troubleshooting and enables rapid response to critical situations.
Data Logger and Cloud Integration
The integrated data logger with four megabytes of storage continuously records all temperature values according to the configured storage frequency. At a 15-second measurement interval, the storage capacity lasts for at least 16 weeks, while at a 60-minute interval, up to 20 years of measurement data can be stored. The data can be downloaded at any time via the web interface as a CSV file and further processed in spreadsheet programs or databases.
Web-Based Management and Visualization
Configuration and monitoring of the Web-Thermometer is conveniently handled via an integrated web interface accessible with any modern browser. After entering the IP address in the address bar, various pages are available, including a home page with current measurements, graphical visualization of temperature trends, and a customizable user page.
The visualization page offers extensive options for displaying temperature trends as line charts. Time periods can be freely selected, and the display dynamically adjusted. For integration into custom dashboards or websites, current measurement values can be dynamically embedded using JavaScript and AJAX. Special tags are available for this purpose, which are automatically replaced with current values when the page is called.
Security Aspects and Password Protection
The Web-Thermometer offers comprehensive security features to protect against unauthorized access. Separate passwords can be assigned for administrator and operator users, with operators having only limited configuration access rights. Transmission uses digest authentication, so passwords are not sent in plain text.
For encrypted communication, HTTPS with TLS 1.2 is available. A self-signed certificate is pre-installed from the factory but can be replaced with an individual certificate signed by a trusted certification authority. Certificate Signing Requests can be generated directly on the device and re-uploaded after signing. Certificate chains are also supported.
For use in security-critical environments, unnecessary services can be disabled. By default, only browser access is enabled; all other communication paths must be explicitly activated. Additionally, it is recommended to operate the device behind a firewall and only open the actually required ports.
Installation and Commissioning
Commissioning the Web-Thermometer is extremely simple. After connecting the NTC sensor to the DB9 socket and connecting to the network via PoE or external power supply, the device starts automatically. With factory settings, DHCP is enabled, so the device automatically obtains an IP address from the DHCP server.
Alternatively, IP configuration can be done using the free WuTility tool from Wiesemann & Theis. This scans the network for all connected W&T devices and allows convenient assignment of IP address, subnet mask, and gateway. IP addresses can also be assigned via ARP command or SNMP.
After IP assignment, further configuration is done via the web interface. Here, sensor names are assigned, storage intervals set, alarms configured, and communication paths activated. An optional adjustment via one-point or two-point compensation enables fine-tuning of measurement accuracy. For highest precision, a JSON-based compensation file with up to ten correction points can also be uploaded.
Firmware Updates and Maintenance
Wiesemann & Theis continuously develops the firmware and regularly releases updates with bug fixes, security improvements, and new features. Firmware updates can be conveniently performed via WuTility. The tool automatically detects all devices in the network, displays the currently installed firmware version, and enables uploading new versions.
The Web-Thermometer features a maintenance-free design. Only the buffer battery for the real-time clock needs to be replaced after about ten years. For this, the housing can be opened and the CR 1632 lithium coin cell exchanged. When operating with NTP synchronization, however, the battery is not strictly required.
For emergencies, a hardware reset is available. By pressing the recessed reset button eight times, either only the passwords can be deleted or the complete configuration reset to factory settings. This is particularly helpful if administrative access data has been lost.
Application Examples and Use Cases
The Web-Thermometer NTC finds application in numerous areas. In server rooms and data centers, it continuously monitors room temperature and alerts when critical thresholds are exceeded that indicate cooling failures. Long-term recording enables analysis of temperature patterns and helps optimize climate control to reduce energy consumption.
In network cabinets and server racks, the device warns of overheating of individual components. Due to its compact design and PoE power supply, it can be easily mounted directly in the cabinet. Automatic email notifications ensure administrators are informed of critical temperature fluctuations even outside business hours.
In building technology and facility management, the Web-Thermometer enables centralized monitoring of offices, conference rooms, and other spaces. Via SNMP or OPC UA, measurement values can be integrated into existing building control systems. Modbus-TCP support allows direct connection to PLC controls for automated control loops.
Production halls, warehouses, and logistics centers also benefit from precise temperature monitoring. The robust construction and high interference immunity make the device suitable for industrial environments. Through cloud connectivity, measurement values can be centrally monitored even across multiple distributed sites.
Comparison with Other Models in the Web-Thermometer Series
The Web-Thermometer series from Wiesemann & Theis includes various models for different requirements. Model 57114 with NTC sensor is particularly suitable for standard climate ranges between minus 45 and plus 75 degrees Celsius. For extended temperature ranges, model 57115 with PT100 or PT1000 connection is available, enabling measurements from minus 200 to plus 650 degrees Celsius with freely extendable sensor cable.
Model 57113 combines temperature, humidity, and air pressure measurement in one device, making it suitable for comprehensive climate monitoring. Model 57120 offers temperature and humidity measurement without air pressure sensor. For industrial applications with multiple measurement points, models 57171 and 57172 with one or two PT100/PT1000 inputs in robust DIN rail housing are available.
Standards, Certifications, and Warranty
The Web-Thermometer NTC complies with all relevant European standards and bears the CE marking. Electromagnetic compatibility meets industrial immunity limits according to EN 61000-6-2 and the stricter emission limits for household and light industry per EN 55032:2015 with A1 class B. This allows unrestricted use in both industrial and office-like environments.
For applications with special accuracy requirements, Wiesemann & Theis optionally offers ISO factory calibration or DAkkS calibration with calibration certificate. These calibrations document the measurement deviation of the specific device and enable traceable measurements for regulated areas.
Wiesemann & Theis provides a five-year manufacturer's warranty on the Web-Thermometer. This exceptionally long warranty period underscores the manufacturer's confidence in the quality and durability of its products. During the warranty period, defects are repaired or the device replaced free of charge.
Economic Efficiency
When evaluating the economic efficiency of the Web-Thermometer, acquisition costs as well as operating and maintenance costs must be considered. PoE power supply eliminates separate power supplies and power cabling, reducing installation costs. The low power consumption of max 3.84 watts causes negligible operating costs.
The long five-year warranty and maintenance-free design minimize failure risk and consequential costs. Firmware updates are available free of charge and can be installed without service technicians. The Wiesemann & Theis cloud solution is also free to use and requires no additional license fees.
Particularly valuable is the contribution to energy efficiency. Through precise temperature monitoring and historical evaluations, air conditioning can be demand-controlled and overcooling avoided. In data centers, even a one-degree Celsius increase in target temperature leads to significant energy savings. The investment in professional temperature monitoring thus often pays for itself quickly.
Summary
The Web-Thermometer NTC from Wiesemann & Theis is a mature and professional solution for network-based temperature monitoring. With its precise NTC sensor, comprehensive network protocols, powerful data logger, and flexible alarm options, it is excellently suited for server rooms, data centers, industrial plants, and building technology.
Easy installation thanks to PoE, the intuitive web interface, and support for modern IoT protocols like MQTT and REST-API make the device future-proof and compatible with a wide range of monitoring systems. The long warranty, high manufacturing quality, and reliable support underscore the quality of the German manufacturer.
For operators of critical infrastructures, IT managers, and facility managers, the Web-Thermometer NTC represents an investment that quickly pays off through operational reliability, energy efficiency, and convenience. The combination of proven hardware, thoughtful software, and comprehensive integration options makes it the first choice for professional temperature monitoring.
