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X-300 | Temperature Logger and Web Thermostat
5 Year Warranty

The X-300 by ControlByWeb is a powerful web thermostat, temperature logger, and temperature alarm that can be monitored and controlled over an IP network.


The X-300™ is two products in one package:

Temperature Logging

First, the X-300™ is a powerful web-based temperature logging instrument that allows you to monitor and control temperatures via an IP network. Up to 8 temperature sensors can be connected at a time.

Temperatures can be viewed in real-time using a web browser. In addition, the X-300™ has many advanced features including email alerts, relay control, a BASIC interpreter, and much more.

Web-Enabled Thermostat

Second, the X-300™ is a 7-day programmable web-enabled thermostat. Users can adjust and set temperatures for heating and cooling systems and view current indoor and outdoor temperatures from any web browser.

As a web thermostat, it provides an attractive control web page that works great on desktop computers as well as smartphones such as the iPhone® and other mobile digital devices.

Thermostat control web page shown on iPhone

Thermostat control web page shown on iPhone®. (iPhone® not included.)

Setup is simple; There is no app to download, no subscription to buy, no software required, and no programming necessary for setup or use.


The X-300 is versatile and has many applications. A few examples are listed below.

The X-300's powerful and flexible design make imagination its only limit.


  • Web-browser based - no software required
  • Email alerts
  • Three, independently controlled 3A relays
  • Field updatable
  • Built-In real-time clock w/ capacitor backup
  • Temperature Logger
  • Supports HTTP, TCP, SNMP, Modbus/TCP
  • Supports additional data logging and management from web services
  • Internal temperature and voltage monitoring for diagnostics
  • Wide operating temperature range
  • Removable terminal connector for convenient wiring
  • Compact, DIN-Rail mountable enclosure
  • Measurement Range: -67°F to 257°F (-55°C to +125°C)
  • Web-Enabled Temperature Logger:

  • The temperature logger can receive data from up to 8 temperature sensors
  • Supports BASIC scripts for advanced configuration
  • Web-Enabled Thermostat:

  • Attractive thermostat user interface
  • Connect up to 3 sensors
  • 7 day programming schedule
  • Connect to single stage heating/cooling system
CE listed RoHS compliant Made in the USA


Temp Monitoring/Logging

Standard configuration for monitoring and/or logging temperatures.

X-300 Standard configuration for monitoring and/or logging temperatures.

Temp Monitoring with Alarm

Basic configuration for an alarm. When the temperature crosses a specific threshold, the alarm will be turned on or off. The alarm could be an audio device such as a buzzer or bell, an indicator such as a lamp, or a functional device such as a fan or heater.

X-300 Monitoring temperatures and sounding a high-temperature alarm

Web Thermostat

Basic connection to a single stage heating/cooling system.

X-300 controlling and monitoring thermostat over the internet.

X-300 Part Numbers (Differences highlighted in green)

X-300-I+PS12-A Relays: 3 (3A 28VAC, 24VDC) Temp: 8 (One temp sensor included) 9-28VDC (One power supply included)
X-300-I Relays: 3 (3A 28VAC, 24VDC) Temp: 8 (One temp sensor included) 9-28VDC
X-300-E (Discontinued) Relays: 3 (3A 28VAC, 24VDC) Temp: 8 (One temp sensor included) POE Class 1 (0.44 to 3.84 Watt) or 5V±5%

More Information:


Where to Buy

Click "Buy Online" to view part numbers and pricing. X-300 is available in the USA and internationally, and can be purchased either from us or an Authorized Distributor.

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Warning: May contain chemicals, including Nickel (metallic), known to the State of California to cause cancer and reproductive harm. -



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