Field service engineers require a range of load cells spanning the separate ranges needed to calibrate their customers' systems. They may also require the assortment to show the way a wide range of force measurements for a singular testing application. The challenge begins when the engineer needs to change the load cell that is associated to his instrument before he can continue. When the new cell is associated to the instrument, the accepted calibration factors need to be installed in the instrument.
Avoiding user-error is a major challenge with by hand data entry or with requiring the engineer to go for from a database of stored calibration parameters. Loading the wrong parameters, or even worse, corrupting the existing calibration data, can lead to erroneous results and costly recalibration expenses. Instrumentation that automatically identifies the load cell being attached to it and self-installing the permissible calibration data is optimal.
Pressure Sensor Transducer
What is Transducer Electronic Datasheet? A Transducer Electronic Data Sheet (Teds) stores transducer identification, calibration and revising data, and manufacturer-related facts in a uniform manner. The Ieee Instrumentation and determination Society's Sensor Technology Technical Committee advanced the formats which include common, network-independent communication interfaces for connecting transducers to microprocessors and instrumentation systems.
With Teds technology, data can be stored inside of a memory chip that is installed inside of a Teds-compliant load cell. The Teds accepted is complicated. It specifies a huge whole of detailed electronic data templates with some degree of standardization. Even when using the data templates, it is not guaranteed that separate vendors of Teds-compliant systems will explain what data goes into the electronic templates in the same way. More importantly, it is not apparent that the calibration data that is needed in your application will be supported by a singular vendor's Teds unit. You must also be sure that you have a way to write the Teds data into the Teds-compatible load cell, whether through a Teds-compatible instrument that has both Teds-write and Teds-read capabilities, or through the use of some other, likely computer based, Teds data writing system.
For precision applications, such as calibration systems, it should also be noted that calibration data that is stored in the load cell is the same no matter what instrument is associated to it. Additional payment for the instrument itself is not included. Matched systems where a field service calibration group might be attaching separate load cells to separate instruments can present a problem.
Electro Standards Laboratories (Esl) has advanced the Teds-Tag auto identification principles which retains the sharp highlight of self identification found in the Teds accepted but can be implemented simply on any load cell and, when associated to the Esl Model 4215 smart meter or CellMite sharp digital signal conditioner, becomes transparent to the user. Manifold load-cell and Manifold instrument matched pair calibrations are also supported. This can be a important advantage in precision applications such as field calibration services.
With the Teds-Tag system, a small and inexpensive electronic identification chip is settled in the cable that extends from the load cell or it can be mounted within the cell housing. This chip contains a unique electronic serial whole that can be read by the Esl Model 4215 or CellMite to recognize the cell. The cell is then associated to the unit and a accepted calibration procedure is performed. The instrument automatically stores the calibration data inside the unit itself along with the unique load cell identification whole from the microchip. Whenever that cell is reconnected to the instrument, it automatically recognizes the cell and self-installs the accepted calibration data. True plug-and-play execution is achieved. With this principles the calibration data can automatically include payment for the singular instrument so that high precision matched systems can be realized. Moreover, if the cell is moved to someone else instrument, that instrument will recall the calibration data that it has stored internally for that load cell. The Esl instruments can store Manifold load cell calibration entries. In this way, Manifold load cells can form a matched calibration set with Manifold instruments.
Any load cell can be really made into a Teds-Tag cell. The electronic identification chip, Dallas Semiconductor part whole Ds2401, is easily available from distributors or from Esl. The chip is very small, production it easy to fit into a cable hood or cell housing.
Both the Esl Model 4215 smart strain gauge indicator and the CellMite sharp digital signal conditioner are associated to load cells via a Db9 connector with selfsame pin outs. The electronic identification chip does not interfere with the cell's signals. Pin 3 of the Ds2401 is not used and can be cut off if desired. simply connecting pins 1 and 2 from the Ds2401 to pins 8 and 7, respectively, of the Esl Db9 connector will enable plug-and-play operation.
When using off-the-shelf load cells, it is often convenient to find the Ds2401 in the hood of the cable. The cell comes with a enduringly mounted cable that protrudes from the cell housing. At the end of the cable, strip back the insulation from the personel wires and solder the wires into the Db9 connector. The Ds2401 is soldered over Db9 pins 7 and 8, and fits within the connector's hood. For a few dollars in parts and a simple cable termination procedure, you have taken a accepted load cell and transformed it into a Teds-Tag plug-and-play unit.
For applications in which passage to the load cell and cable is restricted, an in-line tag identification module can be simply constructed. A right through in-line cable adapter can couple the Ds2401 electronic tag chip. In this application, the cable adapter is really settled in series with the load cell cable before it is plugged into the Esl instrument. It is also possible to use this technique in applications where separate calibrations might be required on the same load cell. The user may have a singular load cell and instrument, but can change which calibration is auto-selected by simply changing the in-line cable adapter. Since each cable adapter has a separate tag identification chip, the Esl instrument will join together a separate calibration data set with each in-line adapter. This might be useful, for example, if a precision 6-point linearization of the load cell is required in two separate operating ranges of the same load cell.
Now that the load cell has been converted to a Teds-Tag unit, it can be associated to the Esl Model 4215 smart strain gauge indicator or a CellMite sharp digital signal conditioner. The very first time it is connected, a accepted calibration procedure is performed to initialize the cell's calibration data in the instrument. The Esl instruments reserve a range of commerce accepted calibrations including mV/V, shunt, 2-point, or multiple-point calibration. The instrument then automatically detects the presence of the Teds-Tag load cell and matches it with its calibration data. From this point forward, the principles is wholly plug-and-play. Typical start up is now:
1. Plug load cell into the Esl instrument.
2. Turn on the power.
3. You're done.
After they've been initially calibrated on the instrument, changing load cells is done by simply plugging the new cell into the instrument and turning on the power. That's it.
The Esl Model 4215 is a calibration ability strain gauge indicator that has internal nonvolatile warehouse for the calibration data of 25 load cells. Model 4215 combines force channels, encoder position channels, print capabilities, and Rs-232/485 serial communications into a versatile platform.
The versatile Model 4215 is used with tensile testers, strain gauges, extensometers, torque transducers, pressure sensors and position encoders. The Model 4215 features a bipolar range +/- 999,999 display, 24-bit resolution, nonlinearity of 0.005%, and auto load cell identification and setup for 25 load cells. Front panel shunt calibration with two selectable resistors is standard.
Menu buttons have alternate functions for setup menus. Programmed operations include peak hold and tracking, programmable math and function channels, programmable limits, the range of engineering units, position and velocity indication, and user-parameter inputs along with menu scrolling and auto zero. Quad limits output: independent, isolated solid state relays control Ac or Dc signals. The unit features six user-selectable filters. There is a tri-state limit display of On, Off and Disabled. Model 4215 includes a quadrature encoder channel for position and rate readout.
The Model 4215 is dataView software ready for graphical user interface and relationship to a Pc. The dataView software features include: full function point-and-click graphical user interface; plug and play operation, full speed data acquisition and plotting; data export into spread sheets; store and recall data files; create and retrieve configuration files; and article generation.
The CellMite is a contract digital signal conditioner that connects directly to a accepted strain gauge based load cell, extensometer or pressure sensor and simultaneously generates a serial digital output for relationship to a Pc as well as a +/-10V analog output. It has internal nonvolatile warehouse for the calibration data of 3 load cells. It can be used with Gui software or standalone to replace analog strain gauge signal conditioners. When it identifies a Teds-Tag load cell, it not only auto-installs the corresponding calibration data needed to take measurements from the cell, it also auto-installs gain and offset factors for its 16-bit scalable analog output. The voltage range and offset of the analog output is automatically changed to match the corresponding load cell. This is a suited feature. Using the CellMite in this way is like having Manifold analog load cell signal conditioners all in one, and having them automatically removed, installed, and matched with a load cell, all without any user intervention.
The CellMite compensates for transducer nonlinearities using its integrated 6-point calibration ability not found in accepted signal conditioners. Its multi-drop Rs232 serial port, unit addressing capabilities, and simple command set allow for relationship of Manifold units in a serial network configuration.
CellMite features the ability to go for in the middle of three transducers, multi-point and mV/V calibration, remote sense excitation, and a 24-bit internal resolution. Functions include tare, peak and valley. The engineering units supported include: in, cm, mm, %, Lb, Kg, N, mV/V and user-defined.
The CellMite operates with whether CellView Lite Gui Software, CellView Multi-Unit Display Gui Software or with software drivers. The CellView software features a turnkey data acquisition system. Data, calibration, and sensor test facts can be saved and exported to spreadsheets. The software allows the operator to setup a test to start and/or stop automatically with user-selectable trigger events and delayed triggering.
The CellMite is ideally suited for in-situ transducer conditioning and distributed process measurements. CellMites are addressable for a Serial Network. The software guides the user through sensor calibration and through adding and removing networked units. The CellMite force determination units can be networked along with the CellMite Lvdt Ac excitation digital signal conditioners.
Electro Standards offers a house of CellMites including singular and dual-channel units, encased, Din rail, and board configurations. Units are available with and without displays. A CellMite is available for wireless communication up to 1500 feet. A CellMite is also available with both Lvdt and force determination capabilities.
Electro Standards Laboratories has expertise on load cell electronics, digital signal conditioning, data acquisition systems, and associated applications. A knowledgeable force of sales engineers is available to support customers with the accepted products offered on the Esl Website and with institution designs for specific applications. The enterprise has been in enterprise for over 30 years designing sufficient engineered solutions.
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