Fourth IEEE International Caracas Conference on Devices, Circuits and Systems, Aruba, April 17-19, 2002 zyx DATA ACQUISITION DEVICE WITH PACKET BASED COMMUNICATION PROTOCOL FOR ENGINE MONITORING Rafael E. Alonso, James Leffew, Sangeetha Shreinivasan, Wilfrido Moreno University of South Florida, 4202 East Fowler Avenue, ENB zyxwv 1 18 Tampa, Florida 33620 E-mails: realonso@eng.usf.edu, leffew@eng.usf.edu, sang-7@rediffinail.com, moreno@eng.usf.edu zyx Abstract- In the new trend of high performance motors with highly sophisticated engines and low emission control systems, the data transfer for normal service maintenance and repairs has increased to such a complex level that it requires dedicated computer systems. This may lead to downtime due to minor faults in components of the system. The proposed basic portable computer design involves normal signal measurements like voltage, resistance, temperature and revolutions per minute of the crankshaft and the on board computer data stream acquisition. The objective is a simple device, which is upgradeable and capable of managing the data acquisition (DAQ), of different signals generated by the system and the transfer of information from the actual point of activity to a remote location using the existing communication systems like serial through a local phone line or DSL. Sending information through regular and shared communication channels increases the computing power of the system by making it an extension of the normal PC. The study presents a simple design system, which is based on an analog-digital signal- processing component, which acts as a DAQ, a microcontroller and a MODEM that is used as an interface between the remote system and the central data service. Taking advantage of modem electronics with modem communications, this system can be developed and the expected results can be achieved. 1. INTERCONNECTION MODELS: With respect to communication systems, there is always an origin, a path and an end or receiver for the information. Sending information is not necessarily simple. The objective is to concentrate on the communication protocols. These protocols are formally known as packet communications. They can be simple, like a serial direct connection, or complex, like dedicated transfer protocols used for computer data exchanges. The IS0 (International Organization of Standards) has standardized a basic model, which is divided into seven layers. The lowest or first is a basic physical layer that involves the electrical and mechanical properties of the link. The highest or last is a dedicated application layer. names of each layer is as shown in Figure 1. The basic layout and Session layer I__-* _- zy --xXxI zyxwvutsrqpo L- Network layer xx _xl ~- -_I_ Figure 1 The OS1 7 Layer communication Model Physical layer (PHL): This layer incorporates the physical properties of a transport media, which includes the mechanical and electrical characteristics. Also included are parameters such as voltage levels, connectors and protectors. Data-Link layer (DLL): This layer is divided into two sub-layers, the Logical Link Control layer (LLC) and the Media Access Control layer (MAC). This subdivision allows multiple MAC’S to be accessed through a single LLC. The MAC deals with physical addresses, such as those for the Ethemet, which are different from logical addresses like those for the 1P. Network layer (NWL): This layer deals with logical addresses and provides routing through the network nodes. This layer uses the IP and ICMP protocols. Additionally, this layer provides different protocols that are used by the transport layer. Transport layer (TRL): This layer is responsible for the reliability of the link and maintains the Transmission Control Protocol (TCP) under its 0-7803-7380-4/02/$17.00 zyxwvutsrq 0 2002 IEEE 1029 - 1