Practical Considerations for IoT Applications: Part 2
Sep, 06 2016
So, the decision has been made to move forward with an IIoT application, that is great news! Now, you need to address practical considerations of the IIoT system itself and how the implementation will work. Your application will monitor an asset (such as an electric motor, tank, filter, or freezer), most likely remotely. There are many common mistakes made at this stage and things most people would not think to look at. These include things like power, environmental concerns, data reporting, and connections to the internet.
First consider how the monitor will be powered. There are usually two choices, either line power or battery power. Line power basically is hardwiring or plugging in the monitor to AC power that is present all the time. This allows the monitor to be on constantly. Battery power is for situations where there is no line power or it is unreliable. The operation of a battery powered monitor is quite different because it has to sleep most of the time or it will deplete the battery too soon. Because it sleeps, the monitor can only measure parameters and report them when it wakes up at pre-determined intervals. The line powered monitor on the other hand is always on and can measure parameters continuously. Sometimes the decision is made for you by what power source is available at the site or the fact that the monitor needs to be awake constantly in order not to miss an important event. However, it is possible for a battery powered monitor to wake when an event happens if a sensor can detect that event and send a signal to interrupt the monitor while it is sleeping.
Next, consider what environment the monitor will be in. Will the monitor be indoors or outdoors? If the monitor is inside, will the climate be controlled or uncontrolled? The easiest environment for a monitor would be inside an office that is heated and cooled all year long. Then the monitor can be made out of less expensive materials, like plastic housing instead of metal, and its components would not have to be as rugged. An industrial environment, even if it is inside, may not be climate controlled and the monitor would be subject to temperature swings. Also, many industrial settings are dirty and rougher so the monitor would need a hardened enclosure and ideally have no openings such as a fan that would allow dirt to get inside of it. If the monitor will be located outside then its housing needs to be rated for outdoor use in order to protect it from rain and dust. Any cables running in or out of the enclosure would need sealed cable glands to prevent moisture and dust from entering. If the monitor is mounted on a mobile asset, then the monitor would need to be ruggedized to withstand not only extreme temperatures, rain, and dust, but also vibration. Mobile monitors can be the most expensive type due to the challenging environment
Next, consider how the monitor will report its data or information. Being that the discussion is about IIoT applications, this monitor needs a way to connect to the internet. If you are fortunate to have internet service at the site then the connection could be made through a Local Area Network (LAN) (also called Ethernet) cable or Wi-Fi. In most cases, there is no internet service and IIoT applications will make use of a cellular service to make this connection. The monitor will need to have either an Ethernet port or Wi-Fi radio in the case of internet service at the site or have a cellular radio built in if internet service is not present.
Along with deciding how to connect to the internet, you need to consider how the connection with the monitors will actually be done. If there is a single asset at the site, then using an “all in one” monitor that has the measurement and communications functions in the same box is most desired. However, if your site has multiple assets and requires the use of multiple monitors, then having each monitor communicate to the internet by itself may not be the most cost effective. For instance, with a hardwired LAN connection, having to run a separate LAN cable to each monitor may be difficult and expensive. Having multiple cellular connections at one site could eliminate the need to run LAN cables, but that means needing multiple cellular lines of service. A better way to handle multiple monitors would be for them to all communicate with a common gateway, like a hub and spoke architecture where the monitors are out on the wheel and communicate directly (the spokes) to the gateway (the hub). This gateway makes the one connection for all the monitors to the internet. In the case of a cellular connection, only one line of service is needed to handle multiple monitors. To reduce wiring, each monitor could communicate with the gateway wirelessly.
For any device to communicate wirelessly, they need to make use of radio frequency (RF) signals. These RF signals travel in straight lines. They can peek around corners somewhat and bounce off walls, but the best connections are made in straight and clear line of sight fashion. A clear Line of Sight (LOS) means that a transmitter can “see” the receiver without anything in the way. A clear LOS provides the best opportunity for reliable RF communications. Unfortunately, a clear LOS is not always possible. RF signals can penetrate walls but the signal strength is reduced each time it has to do so. Signal strength can also be reduced by passing through vegetation such as trees and bushes. However, not just stationary objects can interfere. Mobile objects need to be accounted for as well. For instance, if the monitor was located down low and the receiving gateway was mounted up high some distance away, you can imagine the RF signals traveling low to high and high to low. Now think about someone parking a big tanker truck in between the monitor and gateway. While that tanker sits there, the RF signal could be seriously reduced. Later, when the truck has moved on, the signal is strong again. That can make for some interesting troubleshooting when you see a gap in that monitor’s reporting.
This brief list of considerations hits the most common issues, but is not exhaustive. It is meant to get your thought processes going about the considerations for an IIoT implementation and help facilitate that discussion with any IIoT product suppliers that you might use. If done properly an IIoT application will help alleviate disruptions and increase productivity in your business processes, not make life harder. Good luck with your new application!
Brad Briggs –Director of Product Development, ATEK Access Technologies