Application description: With today's rising cost of a service call, it becomes more important to know ahead of time if and what service is required on a remote device. From meter readers, to washers and dryers, power generators, water towers, or even the familiar soda machine, the largest part of the operating cost can be in service calls. If the Internet could be used to help communicate the type and nature of a service call to a central dispatch center, service calls could be more efficient and much less costly.
System alternatives: In some cases the Internet is readily available for device access and all that is required is a processor running a TCP/IP stack or similar Internet protocol. This is a reasonably well-known solution, but can be cost-prohibitive in situations where only a very low cost processor is usually required, like a vending machine.
An alternative to the more expensive full Internet device connection would be a custom-designed protocol, maybe using a serial interface between the device processor and PC connected directly to the Internet. This is more cost-effective since the PC can be shared between many low-cost device processors in the vending machines. The drawback to this solution is that the custom protocol is expensive to implement and difficult to expand beyond the initial installation unless the connection infrastructure is exactly the same. However, for a single implementation site, this solution can be a good one.
Another alternative would be to use low-cost remote devices connected to an Internet 'Gateway' using a standard and existing interconnection scheme. This type of solution would have the low cost required by applications like vending machines, but would be easily extended to multiple installations. Solutions with these features are available when using the EMIT architecture from emWare. In this solution, a small kernel of code at the device called "emMicro" communicates functions, variables, events, and messages over device networks such as RS232 or RS485 to a gateway.
Remote soda refills: In this example, a soda machine is one of many located in a ten-story building where every floor has at least four machines, and 10 machines on the main floor where the employee lounge is located. So there are 46 machines in this one building.
Each floor has all of the machines communicating over a common bus called RS485. This bus will allow the machines to be located within 4,000 ft. of each other. Each floor ties into a gateway that will translate the information from the RS485 signal and lite device network protocol into TCP/IP protocol that can then be placed on an Internet accessible LAN. In the office of the service organization, client computers need only a browser like Netscape or Microsoft Internet Explorer to access any device. Using viewing screens created with emWare's "EMIT 4" Application Interface Services, the service organization can view each machine and know how each one is functioning. The program can even be set up to notify the service organization if a temperature goes out of range or a machine needs to be refilled due to high usage. No longer will the service organization lose sales because of an empty machine!
Tools employed: A development kit can aid product design engineers with this type of application or any involving remote device management. As an example, the Avnet Design Services emWare Enabled Motorola GP32 development kit contains a GP32 based circuit board, code warrior software for GP32 code development, emWare EMIT software for client code development, and complete documentation and design examples (www.ads.avnet.com/emWare).