Ethernet thermometer & hygrometer with 8 remote RS-485 sensors and IO

RM-408 is an extended version of TH-355 with added RS-485 interface, to which up to 8 external temperature and humidity sensors RHS-1 can be connected. The device has also 1 local sensor and allows individual configuration of each connected sensor, data logging for ~210,000 records of all 9 sensors (1 local and 8 remote) and real time monitoring of all connected sensors. If a sensor reports out-of-range values, the device can send email messages, push notifications to Android devices, SNMP traps, HTTP request to predefined host or can activate its output relay.

The device has also two digital inputs, capable to work with "dry" or "wet" contacts and one SPDT relay output. The inputs are galvanically isolated and can be used to connect various external sensors, like magnetic door sensor, fire or smoke sensor, water leak sensor, etc. The output relay can be connected as sensor to your alarm or fire system, or to connect sirens, lamps or other suitable devices to it, which provides additional method for events signalling. All monitored sensors and the inputs can activate the relay. If needed, the device can be used even as a two-positional regulator, but should not be used for critical applications, as that's not its primary function.

no maintenance needed

Fast and easy installation

All you need to install and run our devices is your 2 hands and 10 seconds time. Just plug in the ethernet cable and the power jack and you're ready to start. So easy as that!

No unnecessary software

Platform independent

You're using a desktop PC, laptop, tablet or smartphone with Windows, Linux, iOS or Android. That doesn't matter! All you need is just a modern WEB browser and an internet connection.

local data logging

Graphical data representation

Many products from other companies require additional software installation that allows data logging and visualisation. Our products doesn't need this - they have all what's needed onboard!

Modern hardware

Performance and reliability

All of our products are designed and manufactured on the basis of modern and advanced electronic components from leading manufacturers in this field - Microchip, Atmel, Maxim Integrated, On Semiconductor, Texas instruments and others.

Accuracy is important

Precise digital sensor

All of our thermometers and hygrometers are equipped with precisely calibrated high-quality digital sensors from leading manufacturers that guarantee the accuracy of each measurement!

Network connectivity

Access from around the world

No matter if you're at home, at the office or on vacation, your devices are on just one click distance. All you need is a PC, smartphone or tablet with an internet connection. Nothing else!


Comparison table
  • 10/100Base-T ethernet interface
  • high-quality, precisely calibrated digital sensor (certificate)
  • 1 local dust-proof sensor with 1m cable length and 4mm mounting hole
  • measures temperature from -40°C to +120°C
  • measurement resolution 0.1°C, ±0.3°C accuracy
  • measures relative humidity from 0 to 100%
  • measurement resolution 0.1%, ±2% accuracy
  • nonlinearity < 0.1%
  • dew point calculation
  • time-differential measurement of the temperature and the relative humidity (value change per given interval)
  • option to connect up to 8 external temperature & humidity RS485 sensors RHS-1
  • 2 galvanically isolated inputs 3-24V with individual input inversion and time-delay option
  • 1 SPDT (NO/NC) relay output 4A/250V able to operate in 3 different modes
  • graphical representation of the maasured values (demo)
  • email 1, SNMP traps and Android push notifications on out-of-range events
  • 3 different notification ranges for the local sensor - Alert, Warning & Critical
  • 1 notification range for the external sensors - Alert
  • supports TCP, IP, ICMP, ARP, UDP, DNS, TLS, HTTP, SMTP, SNMP, NTP and DHCP network protocols
  • integrated WEB server
  • integrated SNMP v2c server + traps
  • integrated TCP server for remote data logging
  • integrated Modbus/TCP Slave for industrial & building automation systems
  • integrated MySQL client for custom data logging
  • integrated HTTP client for custom client/server applications
  • supports data acquisition from the WEB server in XML and JSON format
  • free push notifications for Android smartphones and tablets
  • volatile data history for the last 24 hours
  • data logging and visualisation for ~210.000 records in internal non-volatile memory for all 9 sensors (1 local + 8 remote) (demo)
  • supports firmware upgrade from the WEB server
  • onboard real time clock with 3V lithium backup battery
  • included 5V power adapter
  • password protected configuration
  • easy configuration
  • compact size (92 x 66 x 28 mm)
  • 3 years warranty
  • 1 supports up to 2048-Bit TLS_RSA_WITH_AES_256_CBC_SHA encryption
The price includes the local sensor only!. The remote sensors are bought separately here!


  • industrial & building automation systems
  • HVAC & refrigeration systems
  • remote data logging and monitoring
  • server rooms and racks monitoring
  • individual client/server applications
  • weather condition monitoring systems
  • fire, alarm and control systems
  • agriculture and livestock breeding
  • chemical industry
  • pharmaceutical industry
  • food industry
  • logistics and warehouses
  • as well as many others...

Order now

1 - 10 264 00
11 + 252 00
  All prices include 20% VAT.

Sensor tolerance (SHT21)

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