Simulating a plant can help you identify problems in your potential deployment before you invest in expensive hardware. By using a simulating tool, you can find out what sensors would be outside of the area of coverage, which sensors will have a low data reliability, and you can test alternate scenarios that fix these issues and find the most effective one.
The first problem you will encounter is creating a realistic estimation of the RF environment in your plant. Instead of creating complex 3D models of every object, you can create "RF Zones" that either enhance or penalize the RF propagations.
For instance, if you want to model a tank, it will likely block all radio communication through it, so you can add a circular RF zone on top of it with 0% propagation. If you have an area that is passed by lots of pipes, you can model it as a rectangular (or circular) RF zone with 50% propagation. The same goes for forests, thin walls or other types of large obstacles.
By using this technique for each large obstacle in your plant, you will be able to create a good estimation of your plant's RF environment.
The second step is to place sensors in your plant. Wherever you will need a sensor (pressure, temperature, level, etc), just place a Radio Node next to that area. You will have to place the Access Point of your Gateway so that it will have as many nodes in its area of coverage as possible. You can do this manually or use map overlays to see where the most dense area is.
The third step is starting the simulation. When doing this, you will be able to see how the network forms, how router nodes get other nodes to join the network and create redundancy, how packets travel through the network, and other interesting statistics. By setting the burst period of each device, you can find out the latency and the reliability of the data from each device.
Next you can start optimizing your network. If you find that some sensors do not join the network, this is most likely because they are outside the RF coverage of the Access Point and all its child nodes. To fix this, you need to add repeater nodes starting from the closest covered node to the node in question, making sure that the nodes hear each other as you place them. A repeater node is a node that does not contain a sensor, it just forwards packets from its child nodes.
Nodes with low data reliability are usually nodes that are at the extremity of the network's coverage and have no redundancy. You should always design the network such that each node has at least two neighboring nodes it can hear, so that the Gateway can create redundant paths to and from it. You can create alternate paths by adding repeater nodes.
When simulating the network, you can also find out an estimation of the power consumption of each node. Optimization can be done too by considering power consumption. If you see that a node consumes a lot more power than other nodes, you should add a repeater node next to it. The ideal situation is when all your nodes consume more or less the same amount of power. This way you will need to change batteries more or less at the same time for all your nodes.
Simulating a deployment can save you a lot of effort in designing a WirelessHART network. You can fix issues in the "sandbox" and not spend money on equipment that you will not need in the end, or end up with a poorly designed network.
If you want to test how WirelessHART works without buying expensive equipment, get a copy of the WirelessHART Simulator now! Plan before investing in equipment.
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