Index >> Products >> Monitoring >> Poseidon xxxx

Poseidon2 3268: Ethernet I/O control and sensor monitoring system

Poseidon2 3268 monitors sensors and controls I/O over a network. Logs data, alerts to high temperature, sends e-mails and can be connected to a cloud sensor system. Supports dry contacts (4x digital input), 8 external sensors and can control relay outputs (2x digital output). Supports M2M protocols – SNMP (SNMPv3), Modbus/TCP, XML, and the online portal.

Poseidon2 3268 enables remote I/O control and monitoring over the Ethernet. Poseidon2 is connected to the LAN, reads measurements, and stores the measurements in its internal memory (data logger). I/O can be controlled over the Ethernet. Relay outputs can be controlled over the Web, or according to the value of a connected sensor (“IP Thermostat” or “IP Hygrostat” mode).

Sensors and detectors

Up to 8 sensors, 4 dry contact inputs and 2 relay outputs can be connected.
We supply temperature and humidity sensors (indoor/outdoor), light intensity sensors, DC/AC current and voltage converters. Digital Inputs can be connected to smoke detectors, power failure detectors, water flood detection, and more.

E-mail and SMS alerts

When a value is out of a specified range, Poseidon2 sends an e-mail, a SNMP Trap, or a text message (SMS). Text messages can be sent without any additional software. 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.

Web interface, software, mobile apps

The device can be accessed over the web, using a mobile phone app (Android, iPhone), or through an online portal. Temperature alarms, for example, can be sent by e-mail or SMS.

For data collection and monitoring, we recommend our HWg-PDMS application that displays graphs and exports data to MS Excel. For “IF-THEN” event management (e.g. “If one out of 10 devices fails, send a SMS to the admin”), we provide the “HWg-Trigger” application for Windows.

Poseidon2 3268 can be connected to various third-party applications or cloud services using various protocols (SNMPv3, Modbus/TCP, XML, HWg-Push).

Poseidon2 3268: Ethernet I/O control and sensor monitoring system


Front view    Rear view    Side view

  DIN rail    Rack 1U montage    Poseidon2 3268 Tset

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
  • Digital Outputs (DO): 2x DO relay output (low-voltage NO/NC relay contact)
  • 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 (version 1 and 3), 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

  • Temperature alarms and a thermostat in IT
    Sends an e-mail/SMS alert and turns on additional cooling or ventilation whenever the temperature is high.

  • Switching HVAC / ventilation in a cabinet
    Detects open/closed door and controls the electronic lock.
  • Remote I/O control and monitoring over the Ethernet
    Monitors a remote environment, sensor values can be fed into any SNMP system. Enables remote reading of dry contact inputs and remote control of relay outputs (to turn on HVAC, restart a server, start a diesel generator, ...).
  • Surveillance systems
    Sensor readings and detector states can be fed to IP camera systems of various brands. Digital Outputs can be used to turn on the lights in a certain zone or open/close gates.

  • 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. Modbus/TCP protocol can be used for integration with SCADA systems.
  • Cooler and freezer monitoring + alarm indication
    Measures temperature and humidity in a cooler or a freezer. When a value is out of a safe range, a relay output is activated to e.g. light up a warning light or sound a horn. Suitable for monitoring storages of food or pharmaceuticals. We recommend the PDMS software to monitor temperature.

  • Temperature and other measurements in a cloud
    Poseidon2 remote monitoring device can be connected to cloud systems. Contact us for details.
  • Online web portal + mobile app
    Poseidon2 can be connected to the online portal. All sensors in an account can be viewed from anywhere using a web browser or a mobile app for Android and Apple.
  • Smart buildings
    Sensor readings can be shared in several applications. Relay outputs can be controlled as remote I/O.

Controlling back-up A/C + remote environment monitoring system

Controlling back-up A/C + remote environment monitoring
  • When the main A/C fails (temperature in the room becomes too high), Poseidon2 3268 turns on back-up A/C and alerts the operator.
  • Remote environment monitoring (temperature, humidity, smoke detector, door contact).
  • A back-up A/C unit is controlled by a Poseidon2 3268 relay output (“thermostat” function).
  • When the temperature in the room exceeds a specified threshold, Poseidon2 sends a temperature alert - warning e-mail or SMS.
  • Smoke detector is powered directly from the power-out output of Poseidon2 3268.
  • SMS can be sent using the HWg-SMS-GW unit or the HWg-Trigger utility for Windows. It works as a temperature monitoring system.
  • Values are logged, the log can be displayed and processed e.g. in the HWg-PDMS utility for Windows.
  • Sensor system connected to a NMS (SNMP monitoring system) or SCADA (Modbus/TCP) system.

Connecting I/O over Ethernet

Sensors and I/O over Ethernet
  • Poseidon2 3268 monitors the status of the connected fire alarm system. Alarms from individual zones are connected as dry contacts to Poseidon digital inputs.
  • More DI can be added to the standard 4 DI using the “Expander 4xDI 1W-UNI” unit, for a total of 8 or 12 dry contact digital inputs.
  • At the same time, Poseidon2 3268 measures temperature, humidity, and/or other quantities (light intensity, cabinet door contacts, voltage, etc.).
  • Poseidon2 3268 relay outputs can be connected to a security system or smart home control.
  • DI and sensor states can be easily connected to a SCADA system, a BMS (Building Management System), etc.
  • One Poseidon2 unit can be connected to multiple systems at once.

Connecting I/O to a CCTV system

Connecting I/O to a CCTV system
  • External sensors, detectors, and output control are connected to a CCTV system using a Poseidon2 3268 unit.
  • Detects vibrations, smoke, or reacts to the output (Alarm) of a central security system.
  • A relay output can control an alarm horn.
  • A relay output controls a remote gate. The surveillance system operator authorizes entry/exit with a simple click.
  • A relay output can be used to turn on a lamp to illuminate a zone.
  • A sensor system monitored in IP video management system.
  • Some surveillance systems can accept sensor states.
  • For a list of supported systems, see Third-party industrial / SCADA solutions.
  • When needed, industrial sensors (4-20mA, 0-60V, 0-30A, ..) can be connected, too.


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 and outdoor)

  • –10 to +80°C (14 to 175 °F) 

>> Overview of sensors

Software and applications

>> Software and applications

Connection to the online portal

  • Poseidon2 3268 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 portal can be monitored using a XML interface.
  • Cloud sensor: Poseidon2 can be connected to sensor cloud systems. Contact us for details.

Text message (SMS) alerts

Alert SMS can be sent from the Poseidon2 3268 monitoring unit in several ways:

  • Directly over the network using SMS-GW
    A text message can be sent from the Poseidon2 3268 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 3268 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 3268 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 3268 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 3268 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 3268 supports 8 sensors (quantities). Up to 4 combined temperature/humidity sensors can be connected.
  • What can I measure with Poseidon2 3268?
    Indoor/outdoor temperature and humidity, light intensity, 0-60V DC voltage, 0-30A 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 3268 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 app 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 3268 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.
    A relay output of a Poseidon2 3268 can control a 110/230V output of a PowerEgg.
  • Can I connect voltage detection to DI (“wet contact”)?
    No, digital inputs (DI) are designed for direct connection of a voltage-free contact (“dry contact”), such as a door contact or a relay output.
  • Poseidon2 3268 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 control the relay outputs over the Poseidon2 3268 web interface?
    Yes. If the DO is in the “Local condition” mode, turn off this mode first.
  • Can I control a relay output with a sensor? For example, turn on A/C if the temperature exceeds 35°C?
    Yes, the output can be controlled with a "local condition". We call this the web thermostat or “Thermostat mode”. It is configured on the “Outputs” tab, including the thresholds (e.g. 35°C) and the sensor.
  • Can I control a 110/230V relay over IP?
    Yes, the relay output of a Poseidon2 3268 can be controlled over IP using M2M protocols (Modbus/TCP, SNMP, SNMPv3, HTTP/XML and more), acting as an IP relay for 110V or 230V.
    Use a PowerEgg unit to control a 110/230V output.
  • Is it possible to connect Poseidon2 3268 to a cloud?
    Yes, Poseidon2 is a “cloud oriented sensor”. It can be connected to cloud systems as a “Cloud sensor”.
    Use the HTTP-based HWg-Push protocol. Contact us for details.
  • 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 3268 Tset Poseidon2 3268 quick start set with a temperature sensor.
Contains the Poseidon2 3268 unit, a power adapter, a temperature probe (3m cable), door contact, CD and a manual. - product photo
Poseidon2 3268 Poseidon2 3268 unit only.
Remote sensor monitoring over LAN. 4x DI , 2xRJ11 – max 8 sensors (1-Wire UNI), 2x relay output. 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


>> Order



Poseidon2 3268, Ethernet IO, monitoring system, sensor system, temperature alarm, web thermostat, temperature monitoring system,

Cloud sensor, IP relay, remote I/O, ethernet module I/O, environment monitoring system, temperature alert, high temperature warning system, temperature logger, SNMPv3, snmp relay, network I/O, humidity and temperature, IP sensor, Modbus/TCP


Similar and related products


Product banners