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Damocles2 MINI: LAN device with digital inputs and outputs (relays)

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Damocles2 is a product for monitoring and controlling digital inputs and outputs over a LAN. When a digital input is closed, Damocles2 sends an e-mail, a SNMP trap, or a text message to a specified number. As an added advantage, it can be connected to the portal.

Damocles2 MINI is a network device with relay outputs and digital inputs for connecting external detectors. Damocles2 can be connected to various monitoring systems. We support over 50 different third-party SNMP or SCADA applications.

It is typically used as a web relay (also called IP relay, webrelay or snmp relay), an on off switch or remote power control (e.g. remote power off) for remote products, and for connecting to IoT (Internet of Things). Users also use Damocles2 to measure consumption e.g. by connecting a water meter to a digital input (S0 counter).

Digital inputs for detectors and digital (relay) outputs

Four dry contacts can be connected to the Damocles2 MINI digital inputs (DI). Damocles2 MINI provides two digital relay outputs (DO) that can be controlled over a LAN.
The relay outputs can be switched on or off and the input states can be read using a web interface. Remote IO on a Damocles2 can be monitored remotely over the Internet using the SensDesk portal or a mobile app (SensDesk Mobile).

Remote relay

Damocles2 is often used as a remote ethernet relay for Poseidon2. We call this the “Box-2-Box” mode.
A virtual output of the Poseidon2 unit can be connected over the network to a physical relay output of the Damocles2 unit.

E-mail and SMS alerts

Alerts to changes in digital inputs – dry contact states (alarm) can be sent as a SNMP Trap, E-mail, or as a text message (SMS relay). Alerts can be delayed (for example to send an alert if a cooler door stays open for more than 5 minutes). The e-mail function supports TLS encryption.

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.

Damocles2 MINI: LAN device with digital inputs and outputs (relays)


Front view    Rear view    Side view    Bottom view

  Set package    Damocles2 MINI top view    Damocles2 set

HWg-SMS-GW for sending SMS


  • Ethernet: RJ45 (10/100 BASE-T)
  • WEB: Built-in web server (IPv6, HTTP, HTTPs)
  • Data logger: Data logger for more than 250.000 records
  • Digital outputs (DO): 2x DO relay output (low-voltage NO/NC relay contact)
  • Digital inputs (DI): 4x dry contact DI (state detector)
    Pulse counters: 32-bit S0 counter at every DI
    Can be connected to: Door contacts, smoke detectors, 110/230V power supply detector, water leak detector, fan failure detector
  • Power supply: 9-30V DC
  • Operating temperature: -30°C to +85°C (14°F to +140°F)
  • Mechanical: Metal box, 100 x 94 x 25 [mm] (H x W x D) / 260 g – can be mounted on a wall or on a DIN rail.
  • Warranty: 2 years
  • Cloud support: HWg-Push protocol, MQTT
  • Reaction to a change at a DI: SNMP trap, Email (TLS), SMS
  • Sending text messages (SMS) and dialing numbers: Alerts can be sent as text messages (SMS) via a remote “HWg-SMS-GW3” over the network, to a maximum of 5 phone numbers.
  • M2M communication protocols: SNMP (SNMP version 1 and version 3), XML (HTTPs), Modbus/TCP, MQTT, HWg-Push
  • Box-2-Box mode: Remote relay output for other HW group products
  • 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)

Damocles2 product family

  Damocles2 MINI
Damocles2 1208

Damocles2 2404
LAN Interface
DO (Digital Outputs) 2
(Open Collector)
DI (Digital Inputs) 4 12 24
32bit pulse counter on each DI
HWg-SMS-GW support
HWg-Push protocol (required for
SNMP v3 & HTTPs secure protocols
-48V power for Telco
VDO (Virtual Digital Output)
PoE (IEEE 802.3af) support

Usage examples

    Damocles2 MINI - dry contact, ethernet relay, remote I/O, SNMP relay
  • Remote equipment monitoring
    Monitoring of A/C, UPS, security system status (status relays)
  • Remote relay
    Remote ethernet relay connected over a network – physical output of a Virtual Digital Output (VDO)
  • Energy consumption metering
    Counting of pulses from electricity / water / gas meters. Conversion to price per time period using HWg-PDMS and MS Excel.
  • UPS and back-up generator monitoring: Fuel level, diesel generator status, remote start over IP

  • Security systems

    • IP camera surveillance systems (external sensors)
    • Equipment status, access control systems
  • SCADA systems: Connection of external inputs to multiple independent systems
  • Remote IO monitoring and control over the Ethernet (secure)

  • Security applications
    Remote contact monitoring, secure I/O transfer to a central system (HTTPs / SSL security).

  • Smart buildings
    Values from inputs and outputs can be shared in several different applications. Relay outputs can be controlled as remote input/output.

Remote relay for a Poseidon2 unit

Remote relay (dry contact) for Poseidon2, ethernet relay, web relay, webrelay
  • When the main A/C fails (room temperature becomes too high), a Poseidon2 3266 detects this with a temperature sensor.
  • Damocles2 MINI features a relay output that controls a backup A/C unit.
  • The relay output of Damocles2 MINI is connected, using the Box-2-Box mode, to a Virtual Digital Output of the Poseidon2.
  • The thermostat function in the Poseidon2 unit activates the VDO, the signal is carried over the network to Damocles2 MINI, and the backup A/C is switched on.
  • 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.

Secure connection of I/O over Ethernet

Secure connection of I/O over Ethernet, IPv6, SSL, HTTPs
  • Damocles2 MINI monitors the status of the connected fire alarm system. Alarms from individual zones are connected as dry contacts to digital inputs.
  • Damocles2 MINI 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 Damocles2 unit can be connected to multiple systems at the same time.
  • For secure applications, IPv6 or SSL communication over XML (HTTPs) and SNMPv3 can be used.

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

Software and applications

>> Software and applications

Connecting to the online portal

  • Damocles2 MINI can be connected to the online portal.
  • From the SensDesk portal, the remote relay outputs can be controlled.
  • 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: Damocles2 can be connected to cloud systems for IoT (MQTT).

Remote IO connected to the Sensdesk portal

>> About online portal

Text message (SMS) alerts

Damocles2 MINI monitoring unit can send SMS alarms in several ways:

sms alerting from the Damocles2 WebRelay device

  • Directly over the network using SMS-GW
    A text message can be sent from the Damocles2 MINI I/O unit to a specified phone number using the HWg-SMS-GW gateway.
    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 Damocles2 unit, similarly to e-mail recipients.
    One HWg-SMS-GW gateway can be shared by several devices (e.g. the STE2 WiFi/LAN thermometer 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 relay 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 the Damocles2 unit and send alerts via SMS.

Frequently Asked Questions

    Ask for the price or details:
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    Spam protection. How many is SIX times six?

  • What is the difference between Damocles2 and Poseidon2?
    – Poseidon2 reads values from various sensors and only features a few I/O inputs and outputs.
    – Damocles2 only supports dry contact digital inputs and digital outputs, does not support any sensors. Damocles2 features pulse counters at each input and Modbus/TCP protocol support in all models. Only a Damocles unit can work as the output for the Box-2-Box mode using SNMP traps and input/sensor names.
  • I found several different Damocles2 devices. Are there any differences in their functions?
    Damocles2 units only differ by the number of digital inputs and outputs, power options (12V / PoE / -48V) and the type of outputs (relay / open collector).
    All Damocles2 models are the same in terms of protocols and software.
  • Can I control relay outputs using the Damocles2 MINI web page? I.e. use it as a web controlled relay?
    Yes. If the digital output (DO) is in the “Local condition” mode, turn off this mode first.
  • Can Damocles2 MINI measure energy consumption?
    Yes. However, you need an external meter with a pulse output. S0 pulses are then counted at a digital input (DI) of the Damocles2.
    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.
  • Damocles2 MINI supports pulse counting at digital inputs. What happens if the device is restarted?
    Damocles2 MINI features a non-volatile memory that keeps the counter state even if the power supply is interrupted.
    The 32-bit counter (max value: 4294967296) can be only reset over the web interface.
  • Can Damocles2 MINI log values?
    Yes, Damocles2 includes an internal memory for the data logger. Data are kept even if the power goes off. The logger has a capacity for 250,000 records.
  • Is it possible to connect Damocles2 MINI to a cloud?
    Yes, Damocles2 is a “cloud oriented device”. It can be connected to cloud systems as a “Cloud sensor”.
    Use the HTTP-based HWg-Push protocol, MQTT, or contact us for details.
  • Damocles2 supports HTTPs. Can I upload my own certificate to the device?
    Yes, a security certificate can be uploaded to Damocles2. For details, see AN46: HTTPS in Poseidon2 and Damocles2 units.
  • Do you offer a SW solution that will alert me to a failure of a Damocles2 unit?
    Yes, you can use the HWg-Trigger application that runs on any Windows PC.
    Another option is the online service – a portal for HW group devices.
  • What is the maximum number of e-mail recipients for alerts?
    Damocles2 itself can send e-mails to at most 5 e-mail addresses.
    With the online service or the HWg-Trigger application for Windows, email relay alerts to OK/Alarm states can be sent to more than 5 e-mail addresses.
  • 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
  • Can Damocles2 MINI detect the presence of 230VAC (e.g. the input voltage of an UPS)?
    Yes, use the input voltage detection feature of a PowerEgg unit, or any relay with a contact connected to one of the IN1-IN4 “Dry Contact” inputs. A relay output of a Damocles2 can control the 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.
  • 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
Damocles2 MINI set Damocles2 MINI quick start set with a power adapter.
Contains a Damocles2 MINI, a universal power adapter, a CD and a manual. - photo
Damocles2 MINI Damocles2 MINI stand-alone device.
A Damocles2 unit without accessories.
Mount plate E – 1U Mounting bracket for a rack, 1U installation of HWg-Ares, Damocles2 MINI and other products. - photo
Mount plate D Bracket for attaching HWg-Ares, Damocles2 MINI, Poseidon2 3266/68 or other products to a wall. - photo
DIN Rail box set Bracket for mounting on a DIN rail. - photo
HWg-SMS-GW3 Central SMS Gateway – start set
Central 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



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