Doors Open Wide for Industrial Wireless Switch and Sensor NetworksApril 20, 2012 By: Todd Hanson, Honeywell Sensing and Control
Wireless sensor and switch networks are increasingly making inroads into the industrial sensor industry as more manufacturers and end-users explore wireless. The various technologies have matured and there is a growing market acceptance for their use in factories, warehouses, and other types of industrial facilities.
In addition to typical applications such as automated assembly lines and manufacturing systems, Honeywell has seen a growing list of new applications for 802.15.4 wireless networks in the area of access control, with customers using wireless sensors and switches to monitor the status of gates and doors. High security at airports and freight operations (e.g., baggage handling conveyors and tarmac doors), automated security for retail and manufacturing operations, and energy management, including open doors and vents that waste heat and air conditioning, or that are security access points, are all areas where wireless devices can be retrofitted into existing control systems.
One such interesting application is the use of the Honeywell Limitless industrial wireless network to monitor the status of hangar doors at airports.
Figure 1. An aircraft hangar door with a personal cutout door at the lower left
Large aircraft hangar doors often have small, personal cutout doors (Figure 1) that get left open. Opening the main door while the smaller door is unsecured can cause thousands of dollars in hangar and/or aircraft damage. Because the personal door is encased in the folding main door, getting communication cabling and power to the personal door is a significant engineering challenge. As these doors move, traditional wiring is subject to flexing and straining, which can result in communication failures.
Typically, hundreds of feet of cable are required to get the signal back to the door controller. The Honeywell Limitless network consists of wireless limit switches which monitor the door position and a Limitless WDRR Receiver that can talk to up to 14 different switches at a time. The wireless network can provide information regarding the open/closed status of the access door itself, as well as the device diagnostics. Is the door switch functioning and transmitting? How reliable is the signal? If the switches and battery are battery-powered, what are the battery levels? If there is a problem, the Limitless wireless system is easy to troubleshoot compared to a wired solution which can require tearing up hundreds of feet of tarmac to find the break in the cabling. Not only is that expensive, but the possible downtime as the runway or traffic lane has to be closed off, further increases the overall cost.
The wireless system does not require wiring, conduits, clips, or connectors and this lack of mechanical parts increases system reliability, allows easier installation, and eliminates errors. For retrofit applications, it provides a low total cost. If the facility wishes to move or reconfigure the hangars, it is much simpler, faster and less expensive to do so with a wireless solution compared to a cabled one.
ROI Advantages of Wireless Switch Networks
The largest return on investment (ROI) advantage may be for retrofitting existing hangar installations. Installing and running cables is time consuming and expensive and the period of time it takes to install a cabled door access control system can be greater than the time it takes to purchase and install a wireless switch network system. In addition to the labor and material expenses, aviation facilities need to factor in downtime when calculating the ROI advantages of using wireless. Due to a facility's design, it may be impossible to install cables and wireless may be the only practical solution.
Other ROI advantages include ease of troubleshooting and repair and ease of configuration. If there are changes to a facility's access doors or to the monitoring locations, modifying the wireless architecture is easy; just move the switches and you are done. Wireless switch networks also offer the advantages of remote monitoring and diagnostics. The system can be monitored locally on-site or, in the future, can be monitored over the cloud via mobile and remote devices.
Customers are recognizing the value that wireless devices can provide as a cost-effective alternative to traditional wired solutions.
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