SRF612 Wireless Temperature Transmitter

Part No: SRF612 

The SRF612 is used for wireless temperature measurement inside appliances and in ambient environments. 

  • External Thermistor Sensor Probe* Range: -40°C to +125°C / -40°F to +257°F
  • Selectable Scales °C/°F
  • Battery Life: Up to 2 years
  • Warranty: 1 Year

Contact Us Today

*Probes sold separately from base transmitter

SRF612 Wireless Temperature Transmitter

SRF612 Wireless Temperature Transmitter for temperature measurement in SRF600 Wireless Monitoring Systems. The SRF612 Wireless Temperature Transmitter features connectors for up to four external temperature sensors and an external door sensor.

Note: If you wish to purchase a Door Switch or other accessories, along with your transmitter and Probes, please click here to see our current SRF600 Accessories. 

  • LCD screen for local temperature measurement display 
  • LEDs indicate if alarms are active
  • Selectable scales °C/°F
  • Antimicrobial protection to impede development of bacteria, mold, and fungi as additional defense for high-risk environments

Technical Specifications

Name Value
Scales °C and °F
Internal Temp Range

Lithium Battery: -30°C to +60°C

Alkaline Battery: -18 to +55°C

External Temp Range -40°C to +125°C (-40°F to +257°F)
Resolution 0.1°C (0.2°F)
Door Sensor Resolution 5 Seconds
Instrument Accuracy +/-0.1% ±0.2°C / ±0.4°F full range @ +23°C ambient
System Accuracy (+23°C / +73°F) *0°C to +70°C, +32°F to +158°F <±0.3°C / ±0.6°F
*-25°C to 100°C, 13°F to +212°F ±0.5°C / ±0.9°F
Temperature Coefficient +/-0.005 degree/degree
Hi Hi / Lo Lo Alarm Hi Hi and Lo Lo alarms with alarm delay and fully selectable alarms
Alarm Delay 0-60 minutes
Delay is programmable for either Hi Hi or Lo Lo alarms or both independently 
Number of Internal Channels 1
Number of External Channels 4
Case Material

Rubber Over-Molding with BioCote® Antimicrobial


2 Button keypad standard on all models (Wi-Fi Provoke and Action Buttons)

Battery Specifications

(Qty. 4) AA Alkaline Cells


(Qty. 4) L91 Energizer Ultimate Lithium

Battery Life

Up to 1 Year Battery Life with (Qty. 4) AA Alkaline Cells 

Up to 2 Years Battery Life with (Qty. 4) L91 Energizer Ultimate Lithium

Wi-Fi (IEEE 802.11b/G/N) WPA2 Pre-Shared Key
Radio Range Up to 15 meters Indoors ESP-32
Clock Accuracy

20ppm (1 minute/month) at 25°C (+77°F)

Synchronized with the Cloud at least once per day

Logging Memory

Channels Total Records*
1 140,000
2 96,000
3 76,000
4 60,000
5 52,000
6 44,000

*These numbers are absolute maximums and will be lower for multiple periods of data and/or when wraparound has been started.

Logging Frequency Programmable between 1 minute and 60 minutes
Monitoring Frequency 1 Minute
Radio Rate

5 minutes to 24 hours

Battery life is stated for >=1 Hour Radio Rate

Alarm / Active LEDs GREEN LED flashing once per second indicates active logging
RED LED flashing once per second indicates alarm
Green LED indicates acknowledgement of long press of Wi-Fi button
Green LED also indicates successful connection to the Cloud
Status LEDs Green LED indicates main power connected
Red LED indicates Wi-Fi module is powered up
Flashing Yellow LED indicates trying to connect to the Wi-Fi network
Solid Yellow LED indicates Wi-Fi connected
Solid Red/Yellow combined LED indicates the transmitter is connected to the Cloud and communicating
Door Switch Alarms Continuous and Average Continuous and average door alarms with 5 second detection period
Audible Alarm Buzzer Audible alarm buzzer can be deactivated in the task (Can be silenced with button press on the transmitter)
Environmental Protection / Waterproof IP65 
Dimensions L 110mm x W 100mm x D 45mm
Weight 300g
Power Supply Unit (PSU) Optional PSU Part No SRF600 PWR
Maximum Probe Lead Length Not to exceed 30m
Warranty 1 Year


The Mains Power Supply Unit (PSU) serves as the power supply for SRF600 wireless transmitters when battery power is not acceptable or desired. It is suitable for use with the following products;

The Standard Door Event Sensor works with SRF600 Wireless Transmitters to monitor activity on doors such as those on refrigerators and freezers.

The Heavy Duty Door Event Sensor works with SRF Wireless Transmitters to monitor activity on doors such as those on storage areas and large walk-in refrigerators and freezers.

The PST (Thermistor) Air Probe is a damped air probe for use with SRF600 Wireless Transmitters. The probe is connected to a 2.0m lead.

The PST Air Probe Duplex is a damped, dual air probe for use with SRF Wireless Monitoring Systems. Each probe is connected to a 2.0m lead.

The 6-Pin Lumberg Adapter is designed for use with the SRF612 Wireless Transmitter and allows you to connect up to four (4) external 6-Pin Lumberg sensors to one wireless transmitter.