Advantage Page for:

• Product Manuals
• Product Drawings
• Configurators
• Software
• and much more!

TEDS - plug and play sensor configuration

1) What is IEEE 1451

IEEE 1451 is a set of standards that were established to address smart sensor systems and to develop a comprehensive set of sensor and software protocols. It was hoped that the standard would pave the way for seemless connection of many parts of smart sensors and associated hardware and software

2) What is IEEE 1451.2

The first of these standards was IEEE 1451.2. The standard was designed to gain a standard way to specify the device operation and calibration, a standard physical interface between the sensor and the communications device, and the ability to use standardized off-the-shelf components to build smart sensors.
IEEE 1451.2 had considerable challenges that ultimately led to virtually no adoption of it in practical applications.

3) What is IEEE 1451.4

IEEE 1451.4 directs its attention to only the TEDS part of the sensor and signal conditioning system. IEEE 1451.4 adopts a valuable approach by taking a much more simple approach to other smart sensor concepts by simply focusing on the self identification aspects of a sensor. IEEE1451.4 does this by specifying a table of self identifying parameters that are stored in the sensor in the form of a TEDS (Transducer Electronic Datasheet).

4) What is P1451.4

The IEEE1451.4 committee have only published a draft specification. All indications are that the standard will change slightly before it is published in its final format. National Instruments and its sensor partners have decided not to wait for the final version and are suggesting that sensor vendors start producing sensors based on the draft specification. The draft specification is defined as P1451.4 for (P)reliminary release to separate it from the eventual 1451.4 specification.

5) What is TEDS

TEDS is an acronym for Transducer Electronic Datasheet. It is a table of parameters that identify the transducer and are held in the transducer on a EEprom for interrogation by external electronics. The definition of the table is still not fully defined by the IEEE committee so carries the designation IEEE P 1451.4 for preliminary.
Note TEDS is the data contained on a sensor that is defined by IEEE1451.4. Honeywell Sensotec has for the last 8 years used the TEDS concept in its SIG CAL or SIG MOD. This TEDS in the SIG CAL Plug and Play technology is defined by Honeywell Sensotec rather than the IEEE1451.4 standard.

6) What data is carried in 1451.4 TEDS

There are four areas of TEDS data. One is the basic data that identifies the transducer. The EXTENDED TEDS is where all the electrical and physical properties are stored. The USER area is where a sensor user can store data regarding the sensors location, next calibration date etc. The TEMPLATES section has yet to be fully defined by the IEEE1451.4 committee but will likely contain addition data that is distinct for each class of sensor and will be compiled by the manufacturer. An example of this might be the calibration curve for a ASTME74 load cell.

7) What is the output of a TEDS sensor

There are two types of TEDS sensor outputs. Four wire outputs or two wire outputs/two wire ICP outputs (Integrated Charge Pump) used on accelerometers.
In the case of 4 wire systems the standard calls for two additional wires to carry the digital TEDS data. On two wire systems the Digital TEDS data in digital format share the same wires as the analog signal.

8) What is 'Plug and Play'

Plug and Play is the name adopted for the technology surrounding IEEE1451.4. Plug and Play, however, suggests that the user can plug the sensor into the signal conditioning everything is automatically configured and is ready to take measurements. The IEEE1451.4 standard does not explicitly ensure that this is the case. For example, the IEEE1451.4 specification does not, as yet, address the hardware connection by specifying a connector and wiring code nor does it address what to do with the TEDS data once the signal conditioning has read the information off the EEprom. It is up to Sensor manufactures to use the dot 4 standard either passively or actively. Honeywell Sensotec has chosen to use the IEEE1451.4 table actively and provides 'Plug, Play and Calibrate' of the sensor and signal conditioning system.

9) Honeywell Sensotec 'Sig Cal' and IEEE 1451.4

The IEEE1451.4 standard was written around the same EErom as utilized by the Honeywell Sensotec 'Sig Cal'. Conversion of a Sig Cal sensor to IEEE1451.4 requires a software change only. The IEEE 1451.4 defines a passive system only where the table of data that resides in the sensor. 'Sig Cal' on the other hand uses a Honeywell Sensotec defined table of data and then uses that data to set up the SC2000 so that it is ready to run. Sig Cal is true 'Plug, Play and Calibrate'