In the industrial world, wireless telemetry1 is being adopted, as an enhancement to wired applications, for stand-alone applications, and in totally new applications where wiring costs can be too costly or prohibitive. Because of this need, UniTorq looked into the available technologies and decided to develop a Mesh network using the 900MHz ISM band that would provide a useful solution to the industry.
 There are several network topologies that can be used for wireless telemetry. The most widely used networks are Point-to-Point, Point-to-Multipoint and Mesh.
Units in Point-to-Point and Point-to-Multipoint networks both require direct communication with the access points. In an environment that has metal valves, pipe and vessels it can be hard to fi nd a location for an access point that provides dependable communications with each and every end point. Moving an access point to improve communications with one end point will often degrade communications with other end points.
A Mesh network is the most adaptable to the industrial space. In a Mesh network all radios have a transceiver and a repeater in the same device, which means that any unit can communicate to and through any other units. The result is a more robust network. (Figure 2.)
The biggest benefi t of Mesh-enabled telemetry is that all VCM’s can act like repeaters to get a message/packet where it needs to go; each unit can receive, send and/or repeat. The more Mesh devices you have, the better performance you have from the entire network.
The UniTorq VCM Mesh network also features individual Auto-Routing, Auto-Pathing and Self-Healing capabilities. These features make the system even more effi cient and robust.
Auto-Routing
Auto-Routing is a feature which allows the individual radios to determine how they route a packet to its ultimate destination without the path being pre-selected. The Mesh network signals look for the most efficient way home, by this we mean using the least number of hops between radios. The units have been built in capability to constantly monitor the network for signals being sent by its neighbors (units in close proximity) The units listen for the address of each neighboring unit and measure its signal strength. In each UniTorq Mesh unit exists a table that contains the address and signal strength of the neighboring units. When any given unit needs to send a message it chooses the unit at the top of the routing table, which would be the neighbor with the strongest received signal strength. This helps ensure that the message will have the best chance to succeed.
Auto-Pathing
Auto-Pathing occurs when a message cannot find its intended receiver. The unit will automatically choose another path for the message by going to the next unit in it’s routing table.
Self-Healing
Self-Healing occurs when a previously out of commission unit comes back into the network. The re-entry is accomplished by a broadcast message. The units that answer are put into the radio’s routing table along with their signal strength.
UniTorq is constantly developing products to make your valve application and maintenance as intelligent and as cost effective as technically possible. Please contact UniTorq or your UniTorq representative for more information. |
