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Thermal sensor for indoor usage at RS-485 bus (communication over long distances) with a simple communication protocol. The sensor can be used separately but is designed for connection to the Poseidon measuring unit and transmit temperature over SNMP, WEB or XML.

Temp-485 Box2 Flyer
Temp-485 is a thermal sensor communicating over RS-485 bus. The sensor is designed for vertical indoor mounting to walls.

The measured temperature is sent directly in °C by a simple text protocol. Up to 26 sensors of this type can be connected to a single 4-conductor busbar. The busbar uses 4 wires, two with a standard RS-485 line, the other two are used for sensors' power supply. RS-485 communication line works up to 1000m distance.

For temperature measuring the sensor uses semi-conductor element placed in gold-plated board, element measures with accuracy of ± 0.8°C.


long distance temperature measurement probe, kelvin celsius farenheit rs-485 thermometer, simple protocol
  • Extensive temperature measuring systems
  • Industrial measuring and regulation
  • Temperature measuring in grocery, pharmaceutical and other storage buildings
  • Temperature measuring in production and residential premises (option to connect sensors over long-distance using RS-485)
  • With Poseidon unit 2250 – temperature data transmission over Ethernet or Internet
  • With Poseidon unit 2250 – possible logging of up to 100 000 values into internal Flash memory

Basic features

  • Temperature measuring within the range of -10°C to +70°C
  • Communication and sensor state indication by LED
  • Easy wall mounting
  • Communication over the RS-485 line (up to 1 000 m distance)
  • Temperature in simple communication protocol, directly in centigrade degree. Poseidon can convert to Kelvin or Fahrenheit degree.
  • Minimal power consumption, possible power supply by unstabilized voltage
  • The sensor by itself can send a temperature value according to preset time interval, which can be from 1 to 5000 seconds (approximately 1 hour and 23 minutes)
  • The sensor address at RS-485 bus can also be set by jumpers inside the sensor
  • The sensor cooperates with SNMP thermometer Poseidon
    • Temperature transmitting over various protocols HTML, XML, WEB, SNMP)
    • Values log to PC or in Poseidon unit (2250 model)
    • Alarm when safe range is exceeded (SNMP Trap, Email, SMS)

Downloads & Datasheets




Technical specifications

Basic parameters
+ Range of measured temperature -10°C to +70°C
+ Resolution format 0,1 / 0,01°C (L / H mode)
+ Measurement accuracy +/- 0,8 °C in range from -10°C to +70°C
+ Measuring speed Respond to a request within 50ms at maximum, temperature measuring 1x within a second
+ Measuring element DS18B20
+ Communication parameters 9600 8N1
+ Communication line RS-485 / terminations can be activated by an internal jumper
+ Status indication Red indicator, blinks at every measuring
+ Function modes Auto-Report / Question-Answer
  - Auto-Report mode Temperature value is reported automatically at predefined time, period range is 1 .. 255 [seconds]
  - Question-Answer Temperature is reported upon request according to protocol
+ Temperature format „+028.0C<CR><LF>“
+ SETUP mode Terminal for setting the functions, can be accessed after activation by a jumper.
+ Power supply +8V to +30V DC, reverse polarity protection
+ Power consumption Type 10 mA, max. 50 mA (depending on number of sensors on a line)
+ RS-485 line termination Internal resistor 470W,
+ Outside dimensions 80 x 64 x 67 mm



Sensor address setting

Each sensor on RS-485 line must have its unique address for communication with RS-485 bus. This address is presented via small or capital letter and is configurable several ways. Details are available in manual.

Assigning of RS-485 address to Temp-485 sensor:

  • Address configuration via terminal jumper (see picture)
  • Setup mode configuration (console setup mode)
  • Configuration command over RS-485

Sensor wiring

Conductors are connected over terminal or RJ45 connector. Both possibilities can be combined.

Temp-485 can be connected to RS-485 bus in various methods:

  • Direct connection over 4 conductors
    For use in extensive storage buildings. It requires experience with RS485 bus. We recommend this option to very skilled users or professionals or installing companies.
  • RJ45
    Sensors connection through S-Hub or one thermometer directly to RJ45 connector with RS-485 on Poseidon unit.
  • RJ45 directly - Connection of more sensors via S-Hub
    You do not need Poseidon B-Cable to connect sensor over TP cable to RJ45. TP cable with RJ45 connector can be connected directly to terminal board. Use "LAST" configuration (connection detail) if you connect only one sensor. In case you connect sensors to S-Hub unit, use "MIDDLE"
    (connection detail) configuration for every sensor except the last one.:

    • RJ45 connector wiring to 4 pinsTerminal: GND (-) = RJ45: 7 (brown/white)
    • Terminal: Vcc (+) = RJ45: 8 (brown)
    • Terminal: RS-485 (A) = RJ45: 5 (blue/white) + 6 (green)
    • Terminal: RS-485 (B) = RJ45: 4 (blue) + 5 (green/white)

    You can find direct RJ45 cable connection details on the bottom of the Poseidon B-Cable page.



Sensor samples are already available! Products are in stock in several pieces most of the time. Please use the OID ordering numbers on your orders. The price can be found on the Price list page.

OID Device type
600 342

Temp-485 Box2 - photo
Indoor temperature sensor with RJ45 and terminal for RS-485 connection

600 105 Temp-485 - photo
Indoor temperature sensor, brass shaft withtemperature sensor inside the thermometer.
- (Notice: long delivery time, old type, use different one)

Special Accessories

  • Sensor RJ45 MIDDLE cable [600 233] (details)
    About 0,5 meter long cable, connecting 4 pins ( A,B,+,- ) from terminal unit to RJ45 connector. Cable for connection of middle sensors.
  • Sensor RJ45 LAST cable [600 234] (details)
    About 0,5 meter long cable, connecting 4 pins ( A,B,+,- ) from terminal unit to RJ45 connector. Cable for connection of the last sensor in-line.
  • Poseidon S-Hub [600 041] (details)
    RS-485 bus splitter for 8+1 RJ45 connectors and TP cables. S-Hub can supply power all connected sensor.


-> Pricelist (order) 


How to order

  • ShippingFor ordering from abroad (except Slovakia) we accept payment cards. We support VISA and Eurocard/MasterCard.
  • We deliver via FedEx post service. You can have the product within 48 hours from order.
  • Please follow the instructions on the Order page.
    We will confirm your order within 24 hours via e-mail including term of delivery.


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