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Wireless Temperature and Humidity Sensor


OMWT-TEMPRH:Wireless Temperature and Humidity Sensor

Wireless Temperature and Humidity Sensor

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1 year warranty RoHS
  • Transmits up to 180 m (600'')*
  • 64-Bit Unique ID
  • Up to 100 Sensors Can Coexist
  • 2 to 5 Year Battery Life
  • Compact ABS Enclosure
  • Complies with Part 15 of the FCC Rules
  • Internal Loop Antenna


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The OMWT-TEMPRH Wireless Temperature and Relative Humidity transmitter is a battery operated digital temperature and relative humidity sensor with a micro-processor controlled 418 MHz FCC certified radio transmitter. It has an on board time of day clock that allows it to spend most of the time in a low power quiescent state. At predetermined time intervals the clock will wake up the onboard microprocessor. Unique serial number information digital temperature and relative humidity data are read from a semiconductor digital temperature sensor and a relative humidity sensor. This information is combined with a CRC-16 error check and transmitted in a very short data packet that results in a transmitter on time of only 15 milliseconds. This architecture allows the OMWT-TEMPRH to consume very low energy resulting in a battery life of up to 2 years.

The electronics are coated with a conformal rubber material that provides a moisture barrier against condensation. Submersion in water is not recommended. A hole in the top ABS cover permits a special tool to be inserted to activate the service switch. The OMWT-TEMPRH is shipped with the transmitter turned off (anytime the device is to be shipped the transmitter should be turned off or must be placed in a shielded container to prevent interference that might cause shipping problems). Start the device by momentarily pushing the service switch (you will feel the button click). When the service switch is pushed, a data transmission occurs immediately and a special mark is introduced in the ID field of the transmitted data packet to indicate which device is in service or installation.The service switch is also used to put the device in a quiescent mode (no transmissions and very low power consumption). This is the state the device is in when you receive it. Push and hold the service switch for 10 seconds or more to enter this powered down state.

Using the OMWT Series Windows software incoming data being received from OMWT Series Wireless Transmitters can be viewed in a real-time or historical time-base chart or numerical view. High/low alarms can also be set for each transmitter signal with either a visual or audible alarm indication on the PC. Data can also be logged to disk at a user-specified rate in a text file format that can be opened up into Microsoft Excel. The OMWT Series Windows software also includes a DDE Server that can interface the data being received from OMWT Series Wireless Transmitters to other Windows software packages.

Transmission Frequency:

418 MHz
*Transmission Range:
up to 180 m (600')
depending on environmental conditions
Transmission Rate:
10 to 17 seconds random
Operating Temperature:
-40 to 70°C (-40 to 158°F)
Storage Temperature:
-40 to 70°C (-40 to 158°F)
Temperature Accuracy:
±0.5°C from -10 to 85°C
(-18 to 185°F)
Humidity: 0 to 100% RH non-condensing
Humidity Accuracy:
±5% full scale at 25°C
Humidity Response Time:
15 sec in slowly moving air at 25°C
Battery: 3.6V lithium battery included
Battery Life with Transmissions: 2 years
Shelf Life with Battery Installed:
5 years in quiescent mode
FCC Certified: FCC ID: M5ZTHL
38 H x 53 W x 15 mm D
(1.5 x 2.1 x 0.6")
Weight: 43 g (1.5 oz)
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All amounts shown in USD
Note: Each unit comes complete with operator’s manual.
Ordering Example:  (1) OMWT-REC232 Wireless receiver and 1.8 m (6') RS-232 cable with D89F termination, $222.00  plus (1) OMWT-SOFT OMWT Series Windows software (WIN95/98/NT/2000/XP), $100.00, $222.00 + 100.00 = $322.00