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Poseidon HW interfaces for sensor connecting

Individual Poseidon models support several hardware interfaces for sensor connecting. These interfaces along with connectors and related accessories as well as outputs of Poseidon units are described on this page.


RJ connector for sensor connecting The Poseidon supports following interfaces for external sensor connecting:

Binary Inputs (Dry Contact Inputs)

Binary Inputs (Dry contact inputs) to connect sensor to the Poseidon unit
The binary inputs for bistable sensor connecting. "Dry Contact" means direct connection of zero-potencial contact. The inputs indicates only two statuses - "On"/"Off" ("Open"/"Close") which Poseidon analyses as "Normal" / "Alarm".
The Connector wiring can be found in a manual for individual Poseidon model. (>> The list of Poseidon models )

  • Range of measurement: two Statuses: On/Off  (Open/Close or Alarm/Normal )
  • Maximum wiring length: 50 to 300 meters (see the device model)
  • Type of sensor: contact (switching or disconnecting)
  • Power supply: no external power supply
  • Maximal current: 20 mA
  • Distinguishing level: On (stapled contact) = resistance 0Ω to 500Ω.
  • Communication cable: pair cable (phone or twisted UTP cable)
  • Alarm setting: "Normally Open" or "Normally Closed" - configurable over software
  • Sampling period: circa twice a second
  • Sensor address: connector provides the address
  • Disconnecting sensor detection: No


Dry contact inputs diagramTypical sensors connecting to this interface:

  • Open/close door detector
  • Detector of flooding and water level
  • Smoke, fire or exceeding of dangerous gas concentration level detector
  • Movement sensor, output from alarm exchange
  • PowerEgg supports detection of 110 to 230V electric voltage

>> The list of sensors in our assortment

Relay Outputs

Relay outputsThe Poseidon supports digital outputs. It can be controlled via WWW interface (via SNMP, Modbus/TCP, XML) or the output can indicate Alarm statuses on the sensors.

The Poseidon supports two types of outputs:

  • Switch contact relay (Poseidon model 3268)
  • Voltage output to control external relay (Poseidon 1140, 1250, 2251).

See individual Poseidon manual for details(>>The Poseidon types overview)


Notice: The Poseidon supports only two outputs. Use other device for larger amount of outputs, for example a Damocles family product.

  • Output range: On/Off  (Open/Close)
  • Maximum wiring length: 10 to 300 meters (see the device type)
  • Output type: Open/Close contact relay or voltage output (+10V/0V) - see the device type
  • Current range: see the product specification
  • Output control: Remotely over SNMP, Modbus/TCP, XML, WWW interface over Flash setup
  • Special output features: One Output can be used for local alarm status indication. It can not be controlled remotely and the output switches/disconnects automatically, if only one of connected sensor is in alarm status


Typical devices connected to this interface:

  • Local signalization of the alarm status of any sensor - activation of siren or "Alarm" light
  • Remote Reset (restart) of PC or other devices
  • Remote control of relay (option to turn on external heating, cooling or turn off the system)
  • Option to turn off a device (110 to 230V type) over the PowerEgg unit


>> The list of sensors in our assortment

Bus for sensor connecting

The Poseidon supports 2 busses - RS-485 and 1-Wire. The merit of the busses is option to connect 1 to 41 sponsors to one Poseidon unit (10 over 1-Wire and 31 over RS-485). Wiring installation for bus sensors is budget-priced. Both busses can be used simultaneously.


1-Wire UNI (RJ11)

1-Wire UNI is software extension of the 1-Wire bus.

  • 1-Wire UNI sensors:
  • Maximum wiring length : 60 meters of total length per active RJ11 port
    Note: Distance can be limitted with some 1-Wire UNI sensors or with more RJ11 male-female connectors.
  • Sensor power supply: 5V/20 mA from RJ11 connector (can be boosted by "1-Wire hub Power")
  • Number of 1-Wire UNI sensor on 1-Wire bus: see manual of sensor, unless otherwise stated, max. 2 units of 1-Wire UNI sensors on 1 port (connector) of the device

Other parameters or 1-Wire UNI are identical with 1-Wire bus.

1-Wire (RJ11)

1-Wire bus with RJ11 connector to connect sensors to the Poseidon unitThe digital bus from Dallas Semiconductor company, each sensor has unique ID.

  • 1-Wire sensors (>>list):
    • Temperature & Humidity sensors only
  • Maximum wiring length: 60 meters of total length per active RJ11 port
  • Sensor power supply: 5V/20 mA over RJ11 connector
  • Number of sensor on 1-Wire bus: Maximum number of sensors on one active port is limitted by device model
  • Communication cable: phone cable - 4-wire (2-wire in special cases)
  • Alarm setting: Controlling values in the safe range, setting via Poseidon Flash setup
  • Sampling period: 800 ms to 10 seconds (according to the number of connected sensors)
  • Sensor address: Automatically, each sensor has its unique address
  • Detection of sensor disconnecting: Yes, disconnected sensor responds "-999.9" value.
  • Sensor disconnection alarm: Disconnecting of sensor causes Alarm status if sensor indicates alarm (value out of safe range).
  • 1-Wire bus accessories

  • Pin connecting
    RJ11 and RJ12 connectors have the same measurements, RJ12 connects 6 pins, RJ11 only 4 pins.
Port 2 - RJ12
RJ12 RJ11    
1   +5V Power
2 1 - Not used
3 2 Data Transmit Data
4 3 GND Ground
5 4 +5V Power
6   - Not used

Active / Passive 1-Wire port

Active port is RJ11 connector on the Poseidon device. It guarantees full length of wiring and power for defined quantity of 1-Wire or 1-Wire UNI sensors. When you move the sensor from one active port to other one, the sensors seems to be disconnected. You have to run sensors auto-detection again.

Passive port is RJ11 connector on T-Hub splitter or on the 1-Wire sensor in daisy-chain wiring.
It can’t guarantee full length and full power for all following sensors. The power issue can be solved with using the 1-Wire hub Power.



Industrial bus (RS-485)

RJ45 connector to connect up to 31 sensors over RS-485, maximum 1000 metresOver RS-485 up to 31 sensors can be connected over distance up to 1000 meters in industrial applications. We use TP cables and RJ45 connectors for RS-485 line, it is very easy to use them for a common user.

The RS-485 bus consists of blue communication cable pair (pins 4,5), marked as A and B. Power supply 12V for sensors is conducted through the brown cable pair (7,8).
If you use delivered S-Hub unit or B-Cable module, the green cable pair (pins 3,6) is used to RS-485 bus return from the sensor to the hub unit.

  • Maximum wiring length: 1000 meters of total length
  • Supported sensors: Temperature, humidity, current, voltage and other sensor (>> The list of sensors)
  • Number of sensor on RS-485 bus: Up to 31 sensors (see the device model)
  • Power supply: 12V/120 mA on RJ45 connector
  • Power consumption: Power supply from the Poseidon unit is sufficient for up to 3 sensors. Larger number of sensors must be supplied from external source, for example S-Hub unit
  • Communication cable: UTP twisted pair, eventually 4-wirephone cable
  • Alarm setting : Controlling of value in safe range, configurable via Poseidon Flash setup
  • Sampling period: 800 ms to 10 seconds (according to the number of connected sensors, 10 seconds for 41 sensors)
  • Sensor address: Manually, each sensor must have unique address (see the sensor manual)
  • Sensor disconnecting detection: Yes, disconnected sensor responds "-999.9" value
  • Sensor disconnecting alarm: Disconnecting of sensor causes Alarm status if sensor indicates alarm (value out of SafeRange)


Basic characteristics of RS-485

  • RS485 line Daisy chain topology to connect up to 32 devices including Poseidon unitTotal wiring length up to 1000 meters
  • Up to 32 devices on one line (Poseidon + 31 sensors)
  • High immunity against industry disturbance
  • Connecting in Daisy chain, not in star topography.
  • Each device must have its unique address
  • Polarity of conductors must be respected
  • The end and the beginning of wiring must be terminated


Line terminating

The end of the RS-485 line wiring must be terminated. Here are several methods how to achieve it:

  • Internal jumper on some sensors (jumper marked as TERM or TERMINATOR)
  • In case you use B-Cable reduction, choose "LAST" configuration
  • Sensors which do not have jumper or DIP switch (for example DIN bar version), end the bus with external resistor staffed on the end of wiring (for example connect resistor to terminal of the last sensor).
    Value of this resistor should be higher than 120Ω, for short wiring 470Ω is sufficient and you decrease power consumption of all sensors

>> What to do when RS-485 bus doesn't work


RJ45 wiring

  • Standard TP cable cat5 used
  • Brown pair used for power sensors
  • Blue pair used for RS-485 in direction to sensor
  • Green pair used for RS-485 in return direction from sensor back (details about wiring you can find on the S-Hub page)


Terminating of RS-485
1 -
Not used
2 -
Not used
3 /B/
RS-485 back
4 B (-)
5 A (+)
6 /A/
RS-485 back
8 +12V

Sensor address

Sensor address setting, use original address, setup address with jumper or via Poseidon command via TCP SetupEach RS-485 sensor must have unique address. This address can determined via various methods:

  • To use original address of the sensor which is printed on a tag on the sensor (for sensors without jumpers for configuration of address only)
  • To setup address with jumper for some sensors (jumpers marked A0 to A4)
  • To setup address via Poseidon command (via TCP Setup). In the moment of setting sensor address, only one sensor can be connected to Poseidon unit over RS-485 bus.

The sensor autodetection can be realized not only via Flash Setup but also via TCP Setup using terminal access. The advantage of terminal setup is that Poseidon prints addresses of connected sensors and values.


Topology of RS-485 bus

The sensors communicating over RS-485 bus must be serial-connected (daisy chain). In case you need to connect all sensors from one point, to use the S-Hub unit and to connect sensor in star topology is useful.

Serial (Line) topology

You connect individual sensor with each other. This is sometimes called Daisy chain. Advantageous in large buildings over a long distances.

Linear RS-485 wiring topology, sensors connected over RS-485 with 4-wire cable to the Poseidon unit

  • Connect over 4 conductors (we recommend twisted pair for RS-485)
  • Total length of wiring must not exceed 1.000 meters
  • External power supply is necessary for more than 3 sensors
  • The last sensor must be equipped with terminator for RS-485 line (option LAST)



S-Hub wiring

All sensors are connected to one point and you work with RJ45 connectors only. S-Hub is placed in the middle of the structure.

RS-485 star topology, long-distance wiring,


Special accessories

  • The Poseidon B-cable reduction to transfer RS-485 line and power supply from RJ45 to terminal boardPoseidon B-Cable reduction [600 044] (details)
    To transfer RS-485 line + power supply from RJ45 connector to terminal board - 4 conductors ( A,B,+,- )
  • Sensor RJ45 MIDDLE cable [600 233] (details)
    0,5 meter long cable to connect 4 pins ( A,B,+,- ) from terminal board to RJ45 connector. Cable connection for middle sensors.
  • Sensor RJ45 LAST cable [600 234] (details)
    0,5 meter long cable to connect 4 pins ( A,B,+,- ) from terminal board to RJ45 connector. Cable connection for the last sensor in line.
  • The Poseidon S-Hub switch for 8+1 RJ45 connector which can supply powerPoseidon S-Hub [600 041] (details)
    RS-485 line switch for 8+1 RJ45 connectors and TP cables. S-Hub can supply power to all connected sensors.



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