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USB Thermometers

Available for $25 through our ebay store.
These Digi Watchport USB sensors read the temperature and relative humidity. They are used, but shows no visible wear.


  • Collects both relative humidity (RH) and temperature data
  • Temperature compensated RH readings
  • Maximum reading rate: 20 per second
  • Temperature accuracy:
    • ±3.6° F (±2° C) at -40° F to 14° F (-40° C to -10° C)
    • ±0.9° F (±0.5° C) at 14° F to 185° F (-10° C to 85° C)
  • RH accuracy: ±5% at 0-90% non-condensing; ±8% over 90%
  • RH stability: ±1% RH (typical) at 50% RH in 5 years
  • Power consumption: 15 mA (normal),1.0 mA (suspend mode)
  • Maximum CAT5 UTP cable length: 500 ft (152.46 m)
  • USB 1.0 and 1.1 compatible; backwards compatibility for 2.0
  • Configurable Watchport Manager alarm thresholds

What's included

These sensors include a base unit with a USB cable to connect to the host PC. Also included is a sensing device with CAT5 cable to connec to the base unit.


On Windows Vista and Windows 7 machines, the drivers automatically download via Windows update when the sensor is plugged it in. Alternatively, the drivers can be downloaded from the manufacturer's web site (go to and select "Watchport USB Sensors"). For Windows XP, you will need to download the drivers from this web site.

You may also want to download the WatchPort manager from the "Diagnostics, Utilities and MIBs" link on the manufacturers web site (again, and select "Watchport USB Sensors").  This program has some setup and monitoring utilities.  It is an XP program, but works fine on Vista and Windows 7 (just change the directory for data to somewhere that doesn't require admistrator rights to access).

An ASCII command interface (over a virtual COM port) is available for integrating the thermometer with application software.  The documentation for this interface is available from the same manufacturer web site listed above. The Digi virtual COM port does not appear to be compatible with National Instruments LabView.