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Poseidon2 3266: Remote sensor monitoring over LAN

Poseidon2 3266 is a basic device for remote reading (monitoring) of sensors over the network. It measures temperature, voltage, and states of dry contacts (digital inputs) and other external sensors. It sends e-mail alerts to values out of a specified range, or connects to an environment monitoring system. Supports M2M protocols – SNMP (SNMPv3), Modbus/TCP, XML, and the online portal.

Poseidon2 3266 monitors temperature and other sensors over a network in order to create a remote environment monitoring solution. Up to 8 sensors and 4 digital inputs (dry contacts) can be connected. Poseidon2 is connected to the LAN, reads measurements, and stores the measurements in its internal memory (data logger). The device is accessible via WEB and can send e-mails (or text messages).

Sensors and detectors
We supply humidity and temperature sensors in indoor or outdoor designs, light intensity sensors, DC or AC current and voltage converters. Other sensors include smoke detectors, power failure detectors, water flood detection, and more.

When a value is out of a specified range, Poseidon2 sends an e-mail, a SNMP Trap, or a text message (SMS).
No software is necessary to send text messages over the GSM network. All HW group devices can send text messages (SMS) through a single central gateway, the HWg-SMS-GW. Just a single SIM card can serve all your devices.

Poseidon2 3266 can be connected to various third-party applications or cloud services using various protocols (SNMP, Modbus/TCP, XML, HWg-Push).

Typical applications

  • Poseidon2 sends an e-mail if a temperature is too high or a door is open (a dry contact connected to a digital input is closed). It can also monitor power supply status, smoke detectors, and the environment.
  • Poseidon2 3266 is suitable as a remote monitoring system for servers and technology rooms. Measure remotely with Pt-100 and other temperature and humidity sensors.
  • A frequent application is a remote environment monitoring system.
    It is easy to connect smoke detectors, water leak detectors, PIR motion sensors, etc. They are powered from the Poseidon2 3266 unit.
Poseidon2 3266: Remote sensor monitoring over LAN

Front view    Rear view    Side view    Bottom view

DIN rail      Rack 1U montage    Poseidon2 3266 THset 

HWg-SMS-GW for sending SMS


  • Ethernet: RJ45 (10/100 BASE-T)
  • WEB: Built-in web server
  • Data logger: Data logger for more than 250.000 records
  • Sensors: 2xRJ11 – max. 8 external sensors (1-Wire / 1-Wire UNI)
    Can measure: humidity, voltage, current, 4-20mA, illumination, temperature (incl. Pt100, Pt1000) and many other quantities...
  • Digital inputs (DI): 4x DI for dry contacts (state detectors)
    Supports: Door contacts, smoke detectors, 110/230V power supply detector, water leak detector, fan failure detector
  • Power: 9-30V DC
  • Mechanical: Metal box, 100 x 94 x 25 [mm] (H x W x D) / 260 g – wall-mountable, fits on a DIN rail.
  • Warranty: 2 years
  • M2M communication protocols: SNMP (SNMPv3), XML, Modbus/TCP, HWg-Push
  • Text messages (SMS): Alerts can be sent as text messages (SMS) via a remote HWg-SMS-GW over the network. No software is needed.
  • Support for programmers: HWg-SDK
  • Recommended online portal: – free online portal
  • Supported software
    • HWg-Trigger: Control of other IP devices, alarm redirection to SMS
    • HWg-PDMS: Logging, export to MS Excel, reports
    • Third-party software (SCADA systems, Modbus/TCP)

Usage examples

  • Remote monitoring in IT environments
    Measures temperature and humidity remotely over the network, includes a data logger.
    Connects to any SNMP system.

  • Temperature monitoring at several places
    Several Poseidon2 units can be linked to a single account at the online portal. All readings are accessible anywhere using a web browser or a mobile app for Android and Apple.
  • Cooler and freezer monitoring
    Monitor your technology or your food or pharmaceuticals storage.
    We recommend PDMS as the temperature monitoring software.

  • UPS monitoring
    Monitor the states and voltages of uninterruptible power supplies, monitor diesel generators remotely.
    The unit sends an alarm in case of power failure.

  • Surveillance systems
    Sensor readings and detector states can be fed to IP camera systems of various brands.
    External detectors (door contacts, PIR, smoke detectors etc.) can be easily connected to the digital inputs.

  • A/C monitoring:
    A/C failure, power supply failure, temperature too high, or a leak of the coolant.

  • Industrial applications
    Remote monitoring of dry contacts, 4-20mA probes or Pt-100 and Pt-1000 temperature probes.
    Data logger stores the values in the internal memory.

Remote monitoring of the environment in a room (temperature, humidity, smoke detector)

HWg-PDMS: Cabinet temperature monitoring system
  • Remote environment monitoring in a technology room
  • Temperature and humidity measurement, door contact, smoke detector
  • Smoke detector is powered directly from the power-out output of Poseidon2 3266
  • Sends an e-mail or text message (SMS) alert whenever a value is exceeded or the door opened
  • SMS can be sent using the HWg-SMS-GW unit or the HWg-Trigger utility for Windows
  • Values are logged, the log can be displayed and processed e.g. in the HWg-PDMS utility for Windows
  • Connection to a NMS (SNMP monitoring) or SCADA (Modbus/TCP) system

Remote temperature monitoring in coolers and freezers

HWg-PDMS: Cabinet temperature monitoring system
  • Flat-cable temperature probes are placed in the deep-freezers and coolers. The installation is simple, the cable leads by the door seal.
  • The door contact alerts to improperly closed door
  • Temperature in the cooler is logged in the internal memory of the Poseidon2 unit e.g. every 5 minutes
  • E-mail or text message (SMS) alert is sent whenever a value is exceeded or the door is opened for longer than 3 minutes
  • Sensors can be daisy-chained
  • Temperature can be also measured with a calibrated Pt-100 or Pt-1000 probe

Monitoring of industrial 4-20mA, 0-10V, Pt-100 or Pt-1000 sensors

HWg-PDMS: Cabinet temperature monitoring system
  • A converter for two Pt-100 or Pt-1000 temperature probes can be connected to the Poseidon2 monitoring unit.
    The converter supports 2-wire, 3-wire and 4-wire connection of resistive temperature probes.
  • Industrial sensors with the 4-20mA interface can be connected to RJ11 using a converter. The external sensor is electrically isolated.
  • The external 4-20mA probe is powered from the measuring loop. The white converter box is powered from 12VDC (PowerOut output). The converter includes an electrically-isolated current supply for the external 4-20mA probe, providing up to 24V.
  • The 0-60V sensor can be used to measure a voltage of 0-10V or to monitor 12/24/48V supply.
  • Other converters can be connected to RJ11 as sensors: 0-30V AC, 0-20mA DC, 0-80A DC and more..


Detectors (most popular)

FDR26 Smoke Detector

Smoke detector (12VDC power, relay output)

Door Contact

Open door detector

Impaq shock sensor

Vibration detector (12VDC power, relay output)

Gas Leak Detector

Detector of flammable gases (12V, relay output)


Power failure detector (relay output)

Motion PIR detector

Motion detector (12VDC power supply)

>> Overview of all sensors and detectors

Sensors (most popular)

Expander 4xDI 1W-UNI

4x DI (dry contact input) to RJ11

  • RJ11 1-Wire UNI (needs 4 positions)
  • Designed for indoor use

HWg-WLD Relay

Detects flood in a 2D area using a cable

  • RJ11 1-Wire UNI (includes power)
  • Supplied with 2m detection WLD cable

Sensor 60V 1W-UNI

Measures voltage, 0–60VDC

  • Electrically isolated
  • Recommended for measuring –48VDC

30A Current probe 1W-UNI

0–30A AC current sensor for indirect measurement

  • 0-30A current measurement using a split-core transducer
  • Installation without disconnecting the measured circuit

Sensor Light 1W-UNI 3m

Illumination intensity sensor with a 3m cable

  • Indoor use
  • Output 0–100%

4-20mA 1W-UNI sensor

Measures 4–20mA DC current

  • Electrically isolated
  • Power for an external 4-20mA probe

HTemp-1Wire Outdoor 3m

Temperature + humidity (outdoor)

  • –30 to +85°C (–22 to 185 °F) 
  • 0–100% RH   (Relative Humidity)

HTemp-1Wire 3m

Temperature + humidity (indoor)

  • –30 to +80°C (–22 to 185 °F) 
  • 0-100% RH   (Relative Humidity)

Temp-1Wire-Flat 3m

Temperature (in coolers and freezers).

  • –30 to +60°C (–22 to 185 °F) 
  • IP67, 17240 stainless steel probe – Ø5.7mm
  • Flat cable for installation in a cooler

Humid-1Wire 1m
Humid-1Wire 3m
Humid-1Wire 10m

Humidity (indoor)

  • 0-100% RH   (Relative Humidity)


Temperature + humidity (1U size for 19" rack mount)

  • –10 to +80°C (14 to 175 °F)
  • 0-100% RH   (Relative Humidity)

Temp-1Wire 1m IP67
Temp-1Wire 3m IP67
Temp-1Wire 10m IP67

Temperature (indoor & outdoor)

  • –10 to +80°C (14 to 175 °F) 

>> Overview of sensors

Software and applications

    HWg-PDMS: Cabinet temperature monitoring system
  • Configuration: UDP Config  – Configuring the IP address
  • Reaction to events: HWg-Trigger (MS Windows)
    Sends a text message or displays a warning whenever a value is out of a specified range or a monitored device fails
  • Monitoring and logging: HWg-PDMS
    Monitoring software, graphs, database of readings, output to MS Excel
  • Online service for remote monitoring:

  • Third-party software:
  • For programmers: HWg-SDK
    Description of the M2M interface and examples of collecting data and working with the protocols in several programming languages
    (JAVA, PHP, Borland C++ Builder 6.0, Microsoft Visual C++ 6.0, Borland Delphi 6.0, Microsoft Visual Basic & Excel VBA, VB.NET, C code for Linux, JavaScript (AJAX) Microsoft Visual C# 2005 (.NET))

>> Software and applications

Connection to the online portal

  • Poseidon2 3266 can be connected to the online portal.
  • All devices, sensors, values, history and charts can be viewed from anywhere over the web, or in a mobile app.
  • For programmers: Devices connected to the can be monitored using a XML interface.

Text message (SMS) alerts

Alert SMS can be sent from the Poseidon2 3266 monitoring unit in several ways:

  • Directly over the network using SMS-GW
    A text message can be sent from the Poseidon2 3266 unit to a specified phone number using the HWg-SMS-GW unit.
    No software is needed. HWg-SMS-GW should be connected to the same LAN. Sender's phone number is defined by the SIM inserted in the HWg-SMS-GW unit. Recipient's phone number is configured in the Poseidon2 3266 unit, similarly to e-mail recipients.
    One HWg-SMS-GW gateway can be shared by several devices (e.g. Poseidon2 4002 in the picture).
  • With the HWg-Trigger application for Windows
    The HWg-Trigger application can run in the background on any PC with MS Windows. The application checks for device failures, disconnected sensors, or sensor readings outside of the Safe Range. Alarm status can be notified e.g. by sending a SMS to a specified number using a “HWg-SMS-GW” in the same LAN.
  • With third-party software applications
    Many SCADA (e.g. CapTemp) or SNMP (Nagios, Zabbix, ..) applications can monitor the status of Poseidon2 3266 units and send alerts via SMS.

Logging of values

  • Poseidon2 includes an internal flash memory for the data logger. Data are kept even if the power goes off.
  • The logger has a capacity for 250,000 records. For Poseidon2 3266 working as a temperature logger with one temperature sensor and 4x DI, this means enough memory for 230 days (7.5 months) when logging every 300 [s] (5 minutes).

Tip: The HWg-PDMS application can, for instance, read data from the internal memory over e-mail or web interface.

Frequently Asked Questions

    Ask for the price or details:
     - Web:  http://
    Country: *

    Spam protection. How many is SIX times six?

  • What is the maximum number of e-mail recipients for alerts?
    Poseidon2 itself can send e-mails to 5 e-mail addresses at the most.
    With the online service or the HWg-Trigger application for Windows, e-mails alerting to OK/Alarm states can be sent to more than 5 e-mail addresses.
  • Poseidon2 3266 supports 8 sensors but features only two RJ11 connectors. How can I connect more sensors?
    Sensors can be daisy-chained, or connected to a hub: T-Box2 (photo), T-Box (photo) or 1-Wire hub Power.
  • How many temperature/humidity combo sensors can be connected?
    Poseidon2 3266 supports 8 sensors (quantities). Up to 4 combined temperature/humidity sensors can be connected.
  • What can I measure with Poseidon2 3266?
    Indoor/outdoor temperature and humidity, light intensity, 0-60V DC voltage, 0-30V AC current, 4-20mA current, Pt-100 and Pt-1000 external temperature probes, DI (digital inputs), analog PTC and NTC. For details see Overview of sensors.
  • Can Poseidon2 3266 measure energy consumption?
    Yes, it can measure the immediate current or voltage.
    To measure energy consumed over a time period, e.g. [kWh] or [J], we recommend to use the HWg-PWR 3/12/25 device and a M-Bus enabled electricity meter, gas meter, water meter or heat meter.
  • Why does the unit have the Power-Out?
    A typical application involves the use of an external smoke detector, motion sensor etc. These sensors feature a relay output that connects to IN1 – IN4. However, external detectors need power (typically 12VDC). The Power-Out terminal block is convenient for connecting a power adapter (jack) for powering the external detectors.
  • How can I create a graph or protocol with recorded temperatures?
    Use the HWg-PDMS software utility for Windows. Values recorded in the database can be displayed or exported to MS Excel.
    Or, use a suitable third-party software. For a list of over 50 third-party applications, see: Third-party software
  • Do you offer a SW solution that will alert me to an outage of a Poseidon2 unit?
    Yes, you can use the HWg-Trigger application that runs on any Windows PC.
    Another option is the online service – free portal for IP sensors.
  • Is there an app for my mobile phone?
    Yes, several third-party apps for Android and Apple are available here: Android and iPhone mobile apps for HW group products
  • The humidity sensor reading oscillates around the specified SafeRange and I received over 50 e-mails in a single hour. What can be done about it?
    Set the hysteresis for this sensor to about 5% RH. This reduces the number of unnecessary alarm start/end e-mails that would be sent a couple of seconds one after another.
  • Will I lose data in the internal memory (log file) if the power is disconnected?
    No, stored data are protected against power failures. When the memory is full, the data logger overwrites oldest data with new data.
  • Can Poseidon2 3266 detect the presence of 230VAC (e.g. the input voltage of an UPS)?
    Yes, use the input voltage detection feature of the PowerEgg unit, or any relay with a contact connected to one of the IN1-IN4 “Dry Contact” inputs.
  • Poseidon2 3266 features 4 digital inputs for dry contacts (IN1-IN4). Is it possible to connect more digital inputs?
    Yes, use the Expander 4xDI 1W-UNI module – however, it counts as 4 sensors.
  • Can I connect Poseidon2 3266 to a cloud?
    Yes, Poseidon2 is a “cloud oriented sensor”. It can be connected to cloud systems, such as the “Cloud sensor”.
    Use the HTTP-based HWg-Push protocol. For more info, contact us.
  • Can I control relay outputs with Poseidon2 3266?
    No, Poseidon2 3266 does NOT have digital or relay outputs. Instead, use Poseidon2 3268, 3468, 4002 or Damocles products.
  • What is the warranty?
    The standard warranty is 2 years, can be extended upon request.
  • Where can I find the prices of your devices?
    Ask our distributors, or request a quote from us (by e-mail or by filling out this form).

>> Online order form




Product Description
Poseidon2 3266 Tset Poseidon2 3266 evaluation set with temperature sensor. |
Contains Poseidon2 3266, power adaptor, temperature sensor 3m, door contact, CD & manual. - item photo
Poseidon2 3266 THset Poseidon2 3266 quick start set with a combined temperature/humidity sensor.
Contains the Poseidon2 3266 unit, a power adapter, an indoor temperature and humidity sensor (3m cable), door contact, CD and a manual. - item photo
Poseidon2 3266 Poseidon2 3266 unit only.
Remote sensor monitoring over LAN. 4x DI , 2xRJ11 – max 8 sensors (1-Wire UNI). WEB, XML, SNMP, Modbus/TCP.
Mount plate E – 1U Rack (cabinet) mount plate, 1U montage for HWg-Ares, Poseidon2 3266/68 and other products.- item photo
Mount plate D Wall mount plate for HWg-Ares, Poseidon2 3266/68 and other products. - item photo
DIN Rail box set DIN rail mounting set. - item photo
HWg-SMS-GW2 Central SMS Gateway - start set
GSM SMS gateway for sending text messages from other HW group devices over the LAN. Includes an internal GSM modem, an external antenna with 3m cable, a power adapter and a CD. - photo


Poseidon2 accessories


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Poseidon2 3266, cloud sensor, temperature monitoring system, data logger, environment monitoring, measure temperature, humidity and temperature, remote monitoring system, temperature sensor, smoke detector,

power failure alarm, snmp, SNMPv3, Modbus/tcp, measure humidity, measuring device, server monitoring, temperature measurement, remote monitoring, remote measurement, monitoring system, temperature monitoring software, temperature probe, freezer temperature, pt-100, pt-1000, 4-20mA

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