Siemens Dematic Employs LonWorks to Deliver Productivity for Post Offices

The United States Postal Service (USPS) knows how to move packages and letters, but moving mail within their own distribution facilities presented a lesson in efficiency. The solution: Siemens Dematic and its Power Roller Conveyor networked with LonWorks networks.

Siemens Dematic, Rapistan Material Handling Automation Division is the world’s largest material handling company that offers the most advanced package handling conveyor systems in the world. To achieve higher system productivity through an intelligent control network, the USPS engaged Siemens Dematic to provide power roller conveyor systems at several postal distribution centers.

Selecting an Intelligent Conveyor System

The power roller conveyor is used to move mail trays throughout the distribution facility, from sorting machines and other types of equipment to the loading docks. Layouts of the systems vary depending on location and integrated equipment, so Siemens Dematic required system configuration flexibility. LonWorks helped achieve this goal.

“We needed a cost-effective, peer-to-peer network that could be used to distribute intelligence,” explained Keith Anderson, senior project engineer, Siemens Dematic Controls Development. “The Postal Service required a modular system which would allow them to reconfigure systems easily for changing needs or locations. They also wanted access to more diagnostics for quick and thorough identification of problems, which would increase system uptime.”

LonWorks Provides Modular Solution

Without LonWorks, Siemens Dematic would need to hard-wire the entire system with programmable logic controllers (PLC) to meet the need for comprehensive system diagnostics, thus eliminating modularity and introducing a variety of new opportunities for the monitoring system to break down.

“With LonWorks, the system is already modular,” Anderson added. “LonWorks is an ideal network for our application because it allows us to not only distribute the controls but the intelligence as well,” Anderson said. “In our system architectures, we would normally have a custom PLC layer that would interface and control the I/O. With the distributed intelligence of LonWorks, this custom PLC layer is removed.”

Siemens Dematic’s power roller conveyor units include straight conveyors, curves, mergers and diverts. The power rollers have 24vdc motors and reducers built in. Also included are photo-eyes, controllers, zone controller modules and wiring harnesses, while connectors are located on each end of the conveyor unit, allowing it to be plugged into the next unit.

The entire system is controlled by Echelon’s LNS network operating system, which runs on PCs in a central administrative area. Each system device is monitored by a LonPoint DIO-10 Digital Input Output Interface Module. These modules are the key to obtaining the diagnostic data from the devices. The modules interface with the network through Echelon LonWorks zone routers. The lower level network uses Echelon Free Topology 10s, connected to a 1250 backbone network, and i.LON™ Internet servers where more bandwidth is needed. LonTalk adapter PC cards are used to interface to the PCs. Once installed, this comprehensive network brings control of the entire system to a computer screen.

Efficient System Configuration

Siemens Dematic configures the system with a LON interoperable configuration tool that uses ActiveX plug-ins developed for each unit type. These plug-ins are placed via drag-n-drop capability to make up a graphical representation of the system.This interactive system diagram allows for ease of configuration of the LNS database and the conveyors.

After the network is running, the interactive system diagram continues to serve the user. System administrators can drill down on a plug-in to see the status of a device, set user configurable parameters, or even replace a system component. Only the intelligence of the LNS could enable such a powerful GUI to simplify system design, configuration, implementation and maintenance.

The flexibility of this approach also allows for easy reconfiguration of systems, if processes change and require new layouts. “Since we are using the LonTalk protocol, we can also use other LonTalk devices.We simply create an ActiveX plug-in to make it work within the system,” Anderson added.

The Advantage of Intelligence

“An advantage of LonWorks for the Post Office is the system diagnostics which allow them to manage system uptime,” Anderson said. “They can monitor the system continuously, from a central administrative location, to ensure that all parts are working properly.”

With the diagnostics enabled by LonWorks, the system administrator can identify problems quickly and limit costly system downtime. “LonWorks allows the user to analyze the system by zone,” added Anderson. “The zones are typically 30 inches long, so within 2000 feet of conveyor, you can isolate a breakdown to a 30-inch zone.”

System administrators can even solve problems right at the console. “By identifying a jam on the monitor,” explained Anderson, “the user can reverse a conveyor section and solve the problem, reducing the need for on-site maintenance.” The labor savings and downtime containment will save any postal distribution center significant maintenance dollars.

Interoperability Offers “Open” Potential

Anderson sees the open distributed system architecture of the LonWorks network as its greatest advantage, especially for the future of these intelligent systems. Siemens Dematic plans to continually utilize this flexibility on future projects, incorporating more third-party and standard LonWorks products.

System potential can even go beyond the USPS application or similar manufacturing facilities. “I envision the flexibility of this conveyor system adding high value to electronics manufacturing processes where assembly lines are constantly reconfigured,” Anderson stated.

The engineering model enabled by LonWorks can positively impact Siemens Dematic’s return on investment in system design. “The beauty of LonWorks and distributed intelligence is that you don’t have to invest a lot of engineering in it after you have the module designed,” Anderson concluded. “As we say, you just plug-n-convey.”

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