• Serial to Wireless Basics—Part I: Making the Move
• EtherDevice™ Switch EDS-508 Series Wins 2004 Control Engineering Editors' Choice Award
  
• In next month's issue:
  MOXA Sets Sail—DNV and Maritime Applications

• Substation Automation—UC-7420
• Using NPort W2150 to Create a Wireless Network for Bus Billing

• Win a Wireless Device Server

In this series of articles, we examine the basic concepts and applications of wireless device servers. It seems natural to start by examining why you would want to use wireless device servers instead of the now more traditional serial to Ethernet device. Wireless may not be for everyone, but it could be a much more viable option than you previously thought.

There are three basic reasons for adopting a new technology: (1) to save money, (2) to increase the reliability or safety of existing applications, and (3) to expand the types of applications that are available to end-users. Serial to wireless device servers save users money by reducing cabling costs, and since fewer cables are required when using wireless, reliability and safety are improved by reducing the chance that cables are damaged or disconnected. As for the third reason, serial to wireless lets you put your serial devices on wheels. In this respect, the subtitle of this article, "Making the Move," could also have been written as "Making it Move," in which it stands for serial device. Adding mobility to applications that would otherwise be restricted to a fixed location turns out to be one of the prime reasons behind the increasing interest in wireless device servers.

We can classify serial to wireless applications into two basic types—Static and Mobile.

Static Wireless Applications
A typical scenario is on the factory floor, which has serial devices such as CNCs, sensors of various kinds, and control equipment, located at workstations around the floor. In this case, the devices at each workstation are connected to a wireless device server, which sends radio signals to and from the nearest access point. The access points connect by wire to the factory floor LAN, allowing the workstations to share data and coordinate activities. Data can also be transmitted back to a central computer for processing, or for analysis as part of a SCADA system. Since this application uses access points to connect to an Ethernet LAN, the wireless devices are configured for infrastructure mode.

Mobile Wireless Applications
A good example of a mobile application is in a clinic or hospital. The tasks of medical personnel can be made much more efficient by connecting diagnostic equipment to a central data retrieval and monitoring system. This, in turn can make the patient's experience—from diagnosis to treatment to recovery—more comfortable. Mobility is achieved by connecting an automatic blood pressure checker, EKG, and other diagnostic equipment to a wireless device server, with all of the devices housed on a cart. Data from the devices can be sent to a central computer to update the patient's medical record, and for analysis. The doctor or technician can also easily retrieve the patient's health records, and record new diagnoses and comments. This application would also use infrastructure mode.

•  Infrastructure Mode, Ad Hoc Mode, and Basic Installation
•  How Much Money Can You Save with Wireless?
•  Security Considerations
•  Are Radio Waves Robust Enough?

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EDS-508 is an 8-port rugged Ethernet Switch designed for harsh industrial environments. The switch provides a wide range of intelligent network management features, such as a redundant Turbo Ring (recovery time less than 300 milliseconds), IGMP Snooping, VLAN/GVRP, QoS, and e-mail warning by exception. The switch's wide operating temperature range of -40 to 75°C ensures that your Industrial Ethernet will be suitable for most critical environments.

The Moxa EtherDevice™ EDS-508 Series, one of the most significant innovations featured by Control Engineering in 2004, is a valuable and affordable networking solution for the Industrial Automation field.

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Introduction
Bus companies around the world are implementing automatic ticket reader machines that use smart card technology to collect fares from passengers getting on and off the bus. This type of fare collection system allows bus companies to centralize operations. The smart cards are sold in the bus terminal, so that the bus driver does not need to handle large numbers of coins. The bus company can also collect extremely accurate statistics that record details of which routes are most traveled. From the passenger's point of view, the smart card technology provides two very noticeable benefits. It's easier to get on and off the bus, and more buses can run on the busiest routes.

The bus company, however, faces an additional problem. Although the smart card technology essentially eliminates the need for drivers to handle money, the driver must still transfer data manually from the electronic fare box to the bus company's central computer. This task is done manually when the driver logs into the fare system after the bus returns to the terminal, making the driver's job more inefficient and time consuming.

One of Moxa's customers has come up with a very ingenious way to get around this problem. This Payment Terminal manufacturer, who is skilled in hardware design and manufacturing, incorporated Moxa's NPort W2150 wireless device server into their Payment Terminal System. The new WiFi billing data collection system is more efficient, since the fare data is downloaded "over the air" as soon as the bus pulls into the terminal.

System architecture description
This application enhances the existing Automatic Fare Collection System (AFCS) by creating a wireless bus billing system. The following items are required to set up a wireless bus billing system:

1. The central bus station's WiFi environment is connected to the central fare system.
2. Each bus is equipped with a payment terminal system that is connected to NPort W2150's serial port.
3. The billing system and Application Software must auto-negotiate among the Payment Terminal, Billing database, and server.

Overall Benefit
Moxa NPort W2250/2150 Wireless Device Server completes the WiFibus billing system and enables the fare box machine to login to the central fare system automatically when the bus enters the central bus station. This solution reduces the effort required to login to the fare system, giving the driver more time to take care of other tasks that improve the quality of customer service.

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Have you read about Moxa's new wireless device servers? We think these three products—the 4-port NPort W2004 and 2/1-port NPort W2250/2150—are just the ticket for adding mobility and flexibility to your industrial networking applications. In fact, we'd like to give you the opportunity to win a free 1-port NPort W2150.

Contest Information

Wireless Device Server Daily Winner
Contest starts on May 1, 2005
Submit your idea of how to use Moxa's new wireless device servers.Moxa's product managers will review all applications, and then choose winners based on which applications are the most novel.
We will give away 1 NPort 2150 each work day!