Server room control

Server room monitor is a critical task for those who need to administer servers, network devices and so on. Temperature is the most important physical aspect to monitor: if room temperature increases above a critical threshold, servers could stop and services may discontinue. Another critical thing to monitor is power failure. Almost any server room is equipped with UPS systems that kick in when the main power supply goes out. However knowing when this occurs is a different thing. While the more expensive UPS systems have some kind of management and alerting system, the most popular ones don’t have it. Humidity is one more important physical parameter to monitor: high humidity can be more dangerous than a high temperature. Finally, it could be useful to control main door status both for safety reason and to avoid waste of conditioned air. This application shows a simple but effective solution to control a server room. It allows user to detect:

  1. Room Temperature
  2. Humidity
  3. Status of main door (opened/closed)
  4. Main power failure

The application shows also how set up following alarms:

  1. Send SMS (text message) to mobile number if room temperature is higher than 25°C
  2. Send E-Mail if humidity is higher than 60%RH
  3. Turn alarm bell on if door is left open for more than 5 minutes. Bell is turned off after 3 minutes
  4. Send SMS (text message) to mobile number if door is left open for more than 15 minutes
  5. Send SMS (text message) to mobile number if power is done
A server room


Required stuff

We need following things to setup this application:

  • N° 1 AirQ 101 sensor (for point 1);
  • N° 1 AirQ 110 sensor (for point 1 and 2);
  • N° 1 AirQ 305 board or similar with Li-Po battery (for point 3 and 4);
  • N° 1 HomeNET control unit
  • N° 1 magnetic reed switch
  • N° 1 220V alarm siren
  • N° 1 DIN Rail switching power adapter

It’s important to clarify that this list component list is not mandatory: if humidity control is not critical, AirQ 110 is unnecessary, as well AirQ 305 if power failure and control door is needless. On the contrary, it should be important to increase the number of temperature sensor to monitor temperature in each rack. Note that you can also use different control boards, like AirQ 300, with 4 inputs and 2 relays.

Step by step instructions

1Hardware setup

Let’s start with simple tasks: to install AirQ 101 and AirQ 110 sensors. Being battery powered sensors, they can be placed where needed. As rule of thumb, we suggest to try different places before to decide final position. An important trick is to avoid to place sensor too close to air vent or sources of heat. Next step is installation of the AirQ 305 board. The first aspect to take in account is powering: AirQ 305 need a 12 V power adapter to work. Since AirQ 305 come in a DIN rail mount, maybe the best option is to use a DIN rail switching power adapter that powers the AirQ 305. Wiring is shown in the picture below.

Power supply 2 terminal block

Control board power supply with use of a 2-pole terminal

Now suppose to use a 220V alarm siren, it’s mounted between the neutral of main power and the NO contact of a relay of the board; the circuit is completed linking the COM contact of the relay with the live of the main power.

Alarm siren mounting

Alarm siren mounting between AirQ 305 and main power

Magnetic reed switch is useful to detect if main door is open or closed. So you can mount the magnetic reed with the control board. This kind of switch is usually NO switch: contact is open until door remains closed. However, some of them give user the choice providing three contacts: COM, NO, NC. In the wiring schema NO setup is shown.

Magnetic reed mounting

Magnetic reed mounting to an AirQ Networks control board input


2Software setup

Second step is the software. No installation on your PC/Smartphone is needed: in order to use the system with full capabilities, AirQ Networks control unit provides all the necessary: HomeNET (or ColdNET). HomeNET is the application that allows you to do basic configuration and define all the system logic. You can access to the application using a browser, like Google Chrome or Mozilla Firefox. Control unit IP address is generated by DHCP. To obtain your control unit IP, you have to use HomeNET Finder. Open your browser and type the address obtained by HomeNET Finder:

For basic configuration, we suggest you take a look at page Support. After devices installation and pairing, from your HomeNET main view you can see:

Boards status view

Boards status view for a server room based on AirQ Networks devices

In sensors boxes you can see the last data detected and the last detection time. For control board box, if you have installed hardware as described before, if you click on relay1 button, the siren turns on; clicking another time on relay1, the sirens turns off; if the main door is open, the magnetic reed has the contact closed, so in1 of the control board box becomes active. If you go in Setup page you can set a lot of configuration parameters, like HomeNET user and password, system language etc…

Assign names

You can assign names to the sensors, to the board and its inputs and relays. To change the name of the AirQ 101 sensor, click on Name it and insert a name, for example server room temperature. To change the name of the AirQ 300 board, click on Name it and insert a name, for example server room controller. Click to IN1 to assign name door status. Click to RELAY1 to assign name Alarm siren.

Define system logic

To alarm definition, you need to set more complex behaviours by using rules. To add a new rule, from the main view click on the icon rules from the top bar of a device box, or clicking on Rules from main menu.

Send SMS (text message) to mobile number if room temperature is higher than 25°C

From the dashboard, click on rule icon for the temperature sensor to access managing rules page grouped by the temperature sensor. In the add new rule box, you have to define a rule name, a condition and an action. Next video shows how to set alarm:

From the video you can see the <V>Server room Temperature (</V> string. This string is inserted when you click a board value from the list on the left of the pop-up. In the example it’s selected the temperature of the board. When SMS is sent, the <V>Server room Temperature (</V> string will be replaced with the current temperature detected by the board. By default, HomeNET sends SMS and E-Mail with a frequency of 1 hour. If you want to change these settings, go to Setup page and change values in Messages sending frequency section. Not that time values are expressed in seconds.

Send E-Mail if humidity is higher than 60%RH

You have to the define a rule:

  • Condition. “if humidity is higher than 60%RH”
  • Action. “Send an E-Mail”

Next video shows how to do:

Turn alarm bell on if door is left open for more than 5 minutes. Bell is turned off after 3 minutes

You have to define 3 rules for the control board:

  1. Turn off alarm bell after 3 minutes if it’s turned on.
  2. Turn alarm bell on if door is left open for more than 5 minutes.
  3. Turn off alarm bell if the door is closed. This rule is useful for turn off the bell automatically if the door is closed during the the 3 minutes of alarm.

Next video shows respectively how to do the three rules:

From the video you can see that the first rule means if the siren is on, turn it off after 180 seconds; the second rule means if the door is open (this condition will not evaluate after 10 seconds), turn on the siren after 300 seconds. Note the use of duration for the second rule: if it were not for the duration, the first rule turns off the siren but the second rule switch on again. With the duration, the second rule returns to be evaluated only after the door closes and next time will be re-opened. The third rule means if the door is closed, turn off the siren.

Send SMS (text message) to mobile number if door is left open for more than 15 minutes

You have to define:

  • Condition. “if the door is open”: if IN1 of control board = True.
  • Action. “send an SMS”: you have to define an SMS message action;
  • Delay. “for more than 15 minutes”: you have to delay the action for 900 seconds. During this delay, if the condition doesn’t match (because someone closes the door), the rule is resettled and the delay count restarts.

Data observing

HomeNET application offers to you a lot of utilities for data observing. Read HomeNET documentation for complete information. For example, you can observe temperature trend of the rack, status history of door etc…