Monitoring hard to access locations without the need for a power outlet.
While wireless sensors are powered by batteries and can be used a great distance away from the wireless gateway or access point, you may still find yourself needing to place a wireless gateway or access point in a hard to access location that does not have a power outlet. For example, you may need to place a wireless gateway in an attic, crawl space or sump in order to receive a signal from sensors used in those areas. Sometimes you may luck out and have a power outlet in these areas to supply the needed power to your gateway. In the event that you don't, Monnit provides an option for the MonnitLink Ethernet Gateway that allows the unit to be powered over an Ethernet cable.
MonnitLink Ethernet Gateway With Power Over Ethernet:
Power over Ethernet or PoE technology is a system that allows you to pass electrical power safely, along with data, through Ethernet cabling. To use PoE technology with a MonnitLink Ethernet Gateway all you need to do is purchase the PoE version of our gateway and run a PoE enabled Ethernet cable to the location where you would like to place the unit (up to 300 ft). Place the unit in a place where it will be away from water and extreme temperatures and plug the Ethernet cable into the back of the unit. Now you can ensure that hard to access locations can be monitored without the need for running new power supply lines.
What does the “x” mean next to a sensor name in the monitoring software?
When using the iMonnit User Interface or Monnit Express software, you may notice the "Edit" icon change to show a small red "x" in the bottom right corner. The "x" signifies that a sensor configuration has been changed in the software and is queued to update the sensor hardware configuration on its next heartbeat. Once a sensor's configuration has been changed on the wireless sensor hardware, the icon will change back to it's original form. When a sensor has configurations waiting to be written to the hardware, some items may be grayed out in the configuration panels. If an item is grayed out, it means that sensor configurations affecting that value are waiting to be written and the value can not be modified until the sensor hardware has been updated. If a sensor's "Edit" icon does not return to its original state, it can be caused by any of the following.
Sensor Availability:
Because Monnit sensors are battery powered it is critical that the radio remains inactive between transmissions to conserve power. If transmissions from the sensor are increased and left listening for continual communication, the battery life is severely impacted. This forces the software to pass sensor updates to the sensor only after the sensor has turned on its radio and listens for an acknowledgment. During the acknowledgment, the gateway will notify the sensor that the software has a configuration update and from there the network can communicate the updates to the sensor. At this point the sensor acknowledges the configuration update and the software marks the transaction complete (removing the pending transaction flag).
If a sensor is out of range from the MonnitLink Wireless Gateway, communication with the sensor will be lost until it has returned within range. Once the sensor is within range it should automatically update on its next heartbeat. If it does not, you may need to locate the sensor and power cycle it by removing the battery, waiting 30 seconds then re-inserting the battery.
Gateway Lag:
Out of the box, MonnitLink wireless gateways are configured to communicate with the software application once every five minutes. (It uses the same communication protocol as your web browser does while communicating to your bank.) Because of the five minute gateway heartbeat, there is a lag (delay time) between the time the user saves the configuration settings in the software and the time the gateway receives the updates. After the gateway has acknowledged the updates they are queued to update during the sensor's next heartbeat communication. Once the sensor receives the configuration update it will communicate the success back to the software, which will mark the "Pending" transaction as complete returning the "Edit" icon to its original state.
Understanding the Battery Graphic in the iMonnit™ User Interface.
Monnit offers two sensor products with different battery options. The Monnit WIT is our least expensive, and most common sensor line and is powered by a CR2032 lithium-ion battery and has 250mA hours worth of energy. The Monnit WIT2 is powered by two AA lithium-ion batteries and provides the user with 3,000 mA hours worth of energy.
The battery graphic in Monnit's software solutions (iMonnit, Monnit Express and Monnit Enterprise) is represented by five different images:
- Above 75% it shows Full
- Above 50% it shows Three Quarters
- Above 25% it shows Half
- Above 10% it shows One Quarter
- Above 0% it shows red
- At or below 0% it shows Empty
The percentages are configured per the following table:
| Battery Type | 0% | 10% | 25% | 50% | 75% | 100% |
| CR2032 | 2.7V or < | 2.75V | 2.8V | 2.85V | 2.9V | 3.0V or > |
| 2 AA Lith Ion | 2.4V or < | 2.55V | 2.6V | 2.8V | 2.9V | 3.0V or > |
Monnit uses linear interpolation for all values between the given points. For example, a battery voltage of 2.95 is between 2.9 and 3.0. The battery percent is half way between 75% and 100% (or 87.5%) so the display will be rounded to 88%.
Because the power reservoir is small in the CR2032, the voltage can fluctuate between reads. This can cause the reading to change from 50% to 0% by only having a .15V drop at the time of the battery read. For example, if the network encounters any interference and the sensor has to transmit more than once, the battery will display lower than subsequent readings that didn't have to send retries.
A benefit to AA batteries is that they will show a much smoother curve as the batteries drain due to the larger power reservoir.
Using a Monnit Wireless Button Sensor
When placing Monnit wireless sensors, you want to make sure that you have a reliable transmission signal between the sensor and the MonnitLink Gateway. If the signal is too weak you risk having important sensor data missed as well as decreasing the battery life of your wireless sensors due to transmission retries.
Monnit Wireless Button Sensors
Monnit provides a great wireless sensor product that can aid in the process or placing wireless sensors around your building(s). The Monnit Wireless Button Sensor can provide you with a way to test the transmission signal from your desired sensor location before permanently affixing another wireless sensor at that location. The button sensor includes an LED indication system allowing the user to understand the signal quality of a sensors location before mounting.
How to Use a Monnit Wireless Button Sensor for Placing Sensors
Put the button sensor in the exact location where the other sensor will be mounted, then press the button. The light should blink green if the sensor has transmitted successfully. If the light flashes red, press the button again to double check the location. If the light blinks red again, you will need to find a different location for the sensor you wish to place. For a better understanding of the signal quality, log into the iMonnit online system or Monnit Express Software on your computer to see the visual display of signal strength. Here is another handy trick. Log into the iMonnit online system from any web enabled smart phone, so you can check the signal quality without having to return to a computer.
We hope this little tip has helped you understand how you can optimize the placement of your wireless sensors. For more tips on using your wireless sensors or software, please visit the WiSe Guys Tech Tips.
Wireless Sensor Power Management
When dealing with battery powered wireless sensors, there are a many factors that can affect the life span of the battery. We have compiled a list of useful tips to help you understand wireless sensor power management and improve the life of your wireless sensors' batteries.
Battery Power Options
Monnit provides a great wireless sensor product with a small footprint, allowing our sensors to be placed inconspicuously so they do not draw attention. In order for us to achieve this small footprint, our standard wireless sensors are powered by a CR2032 coin cell battery. The provided coin cell battery provides 225 milli-amp hours (mAh). If you require a longer battery life for your application, we currently provide a AA battery option for our wireless sensors that provide 3,000 mAh (~10 times the battery life).
Frequency of Transmissions
How frequently your wireless sensors transmit (heartbeat) can have a severe impact on the life of the battery. A Monnit WIT wireless sensor with a standard coin cell battery transmitting once an hour will last approximately 2-4 years depending on environmental conditions. If you want to preserve the battery life of your wireless sensor, set the heartbeat (transmission interval) as high as your specific application will allow for.
Temperature Conditions
Batteries are electrochemical devices which convert chemical energy into electrical energy. Extremes in temperature can cause the chemical characteristics of the battery to change, causing the battery to burn power faster when hot or not generate enough current when cold. In order to maximize the battery life of your wireless sensors, keep them as close to room temperature as possible (°60 F - °70 F).
Radio Interference and Transmission Retries
The radio transmission of your wireless sensors is a two part process. The sensor transmits its data to the Wireless Gateway Transceiver then listens for a reply transmission to acknowledge that the signal was received. When there is a significant amount of radio noise or interference, your wireless sensors may have to transmit longer in order to send and listen through the interference. If the signal is not received and acknowledged, the sensor will try to transmit again until it receives a successful response. Both of these issues can have an impact on battery life. Monnit wireless sensors operate on the 900MHz frequency that is less crowded than the popular 2.4GHz and higher frequencies, so you already should expect less interference using Monnit WIT Wireless Sensors. To ensure optimal performance of your sensors and batteries, try to avoid areas that have an excess of radio interference from other devices.
Add the MonnitSphere™ Gateway Application to Windows Startup
When using a Monnit Wireless Sensor Network with a MonnitLink™ USB Gateway, the network relies on your computer to communicate sensor data to the online system. If your computer is powered down or restarted, you will have to manually start the MonnitSphere Gateway application for your wireless sensor network to work. The following Tech Tip will show you how to add the MonnitSphere Gateway application to your Windows Startup folder so it will automatically start with your Windows Operating System.
Windows 7, Vista and XP Operating Systems
- Click on the Windows "Start" button, click "All Programs" then click on "Monnit".
- Right-click on "MonnitSphere Gateway" and select "Copy".
- Click on the Windows "Start" button, click "All Programs" and look for "Startup".
- Right-click on "Startup" and select "Explore".
- Right-click on any empty space within the main area of this window and select "Paste".
- You should now see a shortcut for "MonnitSphere Gateway" in this window.
- Close the window by clicking the "X" in the top right corner.
- The next time your computer starts the MonnitSphere Gateway application will automatically launch.
- Make sure to leave your MonnitLink USB Gateway in an active USB port on your computer, and your network will automatically set to "Active" when the application starts.
Optimizing Your Wireless Sensor Network
When dealing with wireless sensor networks, there are a lot of factors that affect the quality and reliability of transmission signals between your sensors and the gateway (receiver). We have compiled a list of useful tips to improve your wireless sensor network.
Position your Wireless Gateway in a central location
Whenever possible, position your wireless gateway in a central location within your facility or home. If the gateway is against an outside wall, the signal will be weak on the opposite side of your building.
Position your Wireless Gateway off the floor and away from walls or metal objects.
Floors, walls and metal structures such as heating ducts and file cabinets, interfere with your sensor network's wireless signals. By avoiding these structural "Signal Killers" when placing your wireless gateway and sensors, you can ensure optimal performance of your network.
Use a Wireless Repeater.
Repeaters allow you to extend the coverage area of your wireless sensor network by repeating the signals between your wireless sensors and the wireless gateway. Place a Monnit Wireless Repeater / Range Extender halfway between your wireless sensors and the wireless gateway, and you will get an immediate boost in your wireless signal strength. The repeater will also act as a central access point for all of the sensors that are within it's range.
Reduce wireless interference.
If you have cordless phones or other wireless electronics in your facility or home, your gateway might not be able to "hear" your sensors over the noise from the other wireless devices. To quiet the noise, avoid wireless electronics that use the 900MHz frequency. Instead, look for cordless phones that use the 5.8GHz or 2.4GHz frequencies.
Are You On The Right Frequency?
When selecting a wireless sensor network there are few things you should consider to ensure that you are selecting the right frequency for your specific needs.
Radio Strength Over Distance
When a radio transmits a signal, that signal gradually loses strength over time and distance. When the transmitter and receivers are too far apart, the receiver can not "hear" the signal. The higher the frequency of the radio (i.e. 2.4GHz is > 900MHz) the quicker the wave loses its strength, resulting in shorter distances a transmitter and receiver can communicate. Side by side, a 900MHz signal will transmit almost 2.5 times further than a 2.4GHz signal. Additionally, the superior performance characteristics of 900MHz products tend to require less energy (resulting in lower power requirements) than wireless products in the 2.4Ghz frequency.
Obstructions to Radio Signal
Another thing to consider when selectiong a wireless sensor network frequency is the environment where it will be used. Higher frequency radios such as 2.4GHz, tend to propagate poorly through walls, trees and other obstructions. Even in line-of-sight situations higher frequency radios lose strength due to the size of the wave itself. A 900Mhz (and 868MHz) frequency has a 12 inch radio wave (from peak to valley) and can penetrate obstacles more efficiently.
Radio Frequency Congestion
An advantage of the 900MHz frequency is that it is not nearly as crowded as higher frequency bands. Blue Tooth devices, standard WiFi networks (802.11.x), Zigbee and other 802.15.4 devices all share the 2.4GHz frequency band creating radio interference. Most consumer electronics on the market today, run in the 2.4GHz band, making it the most crowded band in the market.
Monnit's 900 and 868MHz wireless sensor networks provide a high performance, low power (and extremely low cost) alternative to similar products in the 2.4GHz space. When deploying these networks in North & South America (900MHz) and the EU (868MHz), these products can be used without any additional government approvals.
For additional information about this topic or to have further questions answered, please contact a Monnit WiSe Guy toll free at 801-561-5555 (8-5 pm MST). We will be happy to assist you.
Wireless Sensor Placement
The following tech tip describes the basics of wireless communications and how sensor placement effects how far apart you can place sensors from the gateway.
Monnit WIT™ wireless sensors incorporate a 900MHz/868MHz bi-directional chipset designed to transmit data (and notifications) from the WIT sensor to the MonnitLINK wireless gateway. Being able to create a reliable link between the two points is key to creating and maintaining a functioning wireless sensor network (WSN).
