All Monnit™ wireless gateways can support up to 100 sensors. To expand a network beyond 100 sensors, simply add another wireless gateway to the network.
Monnit's wireless sensor networks currently operate on the ISM 900MHz (902-928MHz) band as well as 868MHz, 433MHz, and 940 MHz radio bands.
Monnit's ALTA wireless products use Monnit’s new Encrypt-RF bank level security, featuring a 256-bit exchange to establish a global unique key, and an AES-128 CTR for all data messages. So security is maintained at all communication points from sensor to gateway, gateway to software, and back again. Learn more about Monnit's Encrypt-RF here.
Monnit's standard wireless products use several features to help protect sensor data in transit. Our proprietary sensor protocol uses very low transmit power and requires specialized radio equipment to operate. Typical wireless devices that operate on non-proprietary communication protocols (Wi-Fi, Bluetooth, Zigbee) operate using different frequency bands so they can't be used to eavesdrop on the radio communications from the Monnit family of sensors. In addition we use a robust packet tampering evaluation routine to ensure that traffic wasn't altered between the sensors and the gateways. This enables us to check for well-formed data packets that only originated from Monnit enabled devices. To further protect data we have algorithms that protect against spoofing and re-transmission of wireless data packets. This is included with the best in class range and power consumption protocol developed for Monnit wireless sensor systems.
The life span of the battery is dependent on a number of factors: how frequently the sensor transmits data (heartbeat), how far the sensor is from the wireless gateway, and obstructions that could cause difficulty in sending data (farther distance and obstructions require that the radio operate at longer intervals to send and receive data). Monnit provides a battery life calculator that estimates the expected battery life you can expect from different types of sensors.
All Monnit wireless sensors come ready to connect to the Monnit Wireless Gateway upon power up with the exception of Wi-Fi and PoE•X sensors.
Monnit MoWi WiFi sensors connect directly to your existing wireless network.
Monnit PoE•X sensors connect directly to your Ethernet network.
Because Monnit sensors are battery powered it is critical that customers leave the radio inactive between transmissions to conserve power. A CR2032 battery that can last for a multiple of years transmits a signal every hour or two, thereby conserving power and in return preserves battery life. (Monnit's recommended heartbeat is not more than once every hour.)
If transmissions from the sensor are increased and left listening for continual communication, the battery life is impacted harshly (maximum battery life could be as little as approx. 2 hours). This forces iMonnit to pass sensor updates to the sensor only after the sensor has turned on its radio and listens for an acknowledgment. During the acknowledgment, iMonnit can notify the sensor that the database (DB) has a configuration update and from there the network can communicate the update to the sensor. At this point the sensor acknowledges the configuration update and iMonnit marks the transaction complete (removing the pending transaction flag).
Similar to the sensors, iMonnit can't instantly initiate communication to the gateway. The reason is, many firewalls and security measures keep intruders from accessing the customer's network. The gateway is configured to communicate with iMonnit out of the box 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 heartbeat of the gateway there is a lag (delay time) between the time the user saves the configuration settings on Monnit's server and the time the gateway checks in to receive the updates. Only after the gateway has acknowledged the updates the sensor checks in and receives them.
During pending transactions it is impossible for iMonnit to know which stage of the process the configuration is in. For example, if a user has set a configuration change to set the sensor's new heartbeat to 30 minutes, the gateway received the request while the sensor still hasn't.
There are certainly other network stability cases, such as if iMonnit modified the configuration to a 3-hour heartbeat to conserve battery life, the following could occur to cause network instability.
The 3-hour change is observed in iMonnit, from here the gateway is ready to talk to the sensor and inform it that the heartbeat should be 30-minutes now. When the sensor checks in and receives the configuration change, it will receive the 30 minute heartbeat rather than the 3-hour heartbeat. If the sensor was to communicate up to the server that it has successfully updated its configuration, iMonnit must assume it has been updated to 3 hours and marks the transaction as complete. This is the reason Monnit marks transactions that require communication with the sensor as "Pending".
To be able to update sensor configurations the user needs to make sure the sensor is communicating well to iMonnit and wait until the pending configuration completes.
iMonnit has a global feature so you can stop notifications from sending emails and text messages to your devices. To turn this feature on and off, do the following: