A combined ISO/IEC/IEEE 21451-4 and -2 data acquisition module

A prototype is described which combines the TEDS-only (-4) and point-to-point serial (-2) versions of the IEEE 1451 standard. The standard, now being renamed the ISO/IEC/IEEE 21451-x smart transducer standards, provides a protocol which permits autoconfiguration (plug and play) and interoperability without operator intervention implemented. The Transducer Electronic Data Sheet (TEDS) is a key feature. While the TEDS-only version has achieved significant acceptance, there are drawbacks to the standard as it stands because it does not specify the digital data format and the TEDS format differs from the rest of the 1451 standard. Specifically, the ISO/IEC/ IEEE 21451-4 Mixed Mode Interface Smart Transducer Standard has a Plug and Play Sensor which includes a TEDS (Transducer Electronic Data Sheet). It is connected through the Mixed-Mode Interface (MMI) to an external data acquisition system whose specification are not specified by the standard. However, the ISO/IEC/IEEE 21450 Smart Transducer Standard does specify the digital data format in detail. Specifically described here is a prototype of the ISO/IEC/IEEE 21451-2 standard for point-to-point serial communication. It consists of a Transducer Interface Module (TIM) and a Network Capable Application Processor (NCAP). The TIM has a transducer (sensor or actuator), associated analog signal conditioner, analog-to-digital converter, TEDS, microcomputer and physical layer driver (RS232). The prototype consists of an NCAP (gateway) connected to a -2 style TIM which has with several -4 ports. The format of the -4 and -2 are differ significantly. Data from the TIM via the NCAP as seen from the Internet must have the 21450 format so that it is necessary to translate the -4 TEDS. An optional “virtual TEDS” is stored at an Internet site. The TEDS on the TIM stores only the address of the TEDS in addition to the Basic TEDS.