Measurement Bus Characteristics and Areas of Application The Measurement Bus arose out of cooperation between manufacturers in the field of manufacturing quality measurement, users from the car industry and the "Physikalisch-Technische Bundesanstalt" (Federal German Authority for Testing, Calibration and Certification) as a typical user standard. It was standardized in September 1989 as DIN 66348 Section 2: "Interfaces and Control Procedures for Serial Measurement-Data Transfer, Start-Stop Transfer, 4-Wire Bus". Range of Applications The Measurement Bus was devised as a low-cost interface for the entire range of industrial test and measurement techniques. This includes tasks in manufacturing quality measurement, in computer-aided quality assurance, in the "small quality control loop" of statistical process control, in the monitoring of manufacturing equipment and processes as well as production data acquisition and machine data acquisition. In addition, it has also been successfully employed for stored program control. Due to its technical characteristics, the Measurement Bus bus is also suited for use in systems and equipment which are subject to calibration regulations. Examples of these are petrol stations, flow measurement devices and weighing equipment. DIN 66348 Section 2 meets the requirements of PTB ("Physikalisch-Technischer Bundesanstalt") Guideline 50.20 for centralized multi-endpoint connections, which is an important requirement for the pattern approval of equipment. - Reliability and Failure Tolerance: The design of the physical characteristics and the data link layer of the Measurement Bus ensure high transmission reliability, even in cases of severe electromagnetic disturbances; it can also detect faulty data blocks. - Availability: This is proven by the failure probability of a bus system. The Measurement Bus, which is a four-wire bus, is the only field bus to have separate transmit and receive lines. - Costs: Installation and interface costs for measurement-bus users are low. Both the hardware costs and the development expenses are in line with those of the widespread serial interface in accordance with RS-232-C or V.24, decoupled. Any commercially available PC can be used as a master station, and simple signal level converters and gateways enable the user to connect older equipment already in use. - Flexibility and User Friendliness: It is simple to install and to put into operation, and in addition maintenance and fault removal are available in cases of failure or breakdown - these factors are particularly important to the user. The demands made of staff are not any higher than for other tasks in industrial electronics systems. Planning and implementing a system with Measurement Bus users can be done and modified quickly; the master station controls the entire bus centrally and can intervene at any time. At the same time the master station is the network service access point for higher-level networks (MAP [manufacturing automation protocol], MMI), which can access the measurement bus network at any time. Long branch lines and the possibility of extending the network as much as is desired allow the user to arrange the equipment without any spatial restrictions. Table 1: Application characteristics of Measurement Bus systems Criteria for manufacturers or users to decide to use the Measurement Bus are, in addition to the capacity to effectively transmit measurement data and parameters in the areas of application mentioned previously, further basic requirements of industrial practice which the Measurement Bus takes into account. In particular medium-sized companies in the fields of manufacturing and process engineering, but large manufacturing companies as well, such as those in the car industry with man-machine-interface (MMI) networks these form the Measurement Bus"s target group. Description The Measurement Bus is distinguished from other field b