Monday, July 14, 2014

New USB Weight Transmitter from Scale-Tron connects Load Cells to a Computer



Scale-Tron Inc. (Canada) - With both power and data direct from the PC computer’s USB port, RL Scale’s 1X3-1945 weight transmitter allows PC applications to access weight or force readings from any load cell assembly with high precision and settling speed. The transmitter has 24 bit resolution and typical noise/jitter of better than 1 part in 100,000 at settling times of ½ second or less. The latest development in ADC chips, a proprietary filtering technique and RL Scales’ 40 years experience in load cell electronics make this possible. A detailed application manual steers the user through the steps needed to interface the transmitter with software for the user’s main application; engineering and software assistance is available on request.

Inputs for up to four 350 ohm load cells are provided by 8-pin Molex Micro-Fit locking type connectors giving low cost and high reliability.

Power is by the built-in USB 5 volt power from the host computer via a standard USB ‘B’ type or 4-pin Molex Micro-Fit connector. Package size is 5.5” x 2” x 1”.

The 1X3-1945 transmitter has been optimized for lowest noise and fastest settling together with high rejection of vibration frequencies; all parameters can be preset from a PC ‘dashboard’ application. This application also allows calibration, monitoring of weight values, measurement of settling time and testing of commands for reading the weight values and setting of operating parameters. The circuit board’s internal firmware can also be modified on a custom basis for different applications.

A major feature of this transmitter is its ability to compensate for the variation of gravity with latitude and altitude. A little known fact, the force of gravity decreases as the distance from the center of the earth increases. Because the earth is spinning, it flattens out towards the equator, which is 43 km wider in diameter than at the poles. This can cause up to 0.5% error in scales that are based on force rather than the balance beam principle - and almost all electronic scales are currently based on force, since the load cell is a force measurement device. Two corrections are provided: the first is applied during calibration and the second is applied during use. This system allows scales to be calibrated at one latitude and altitude and used at any other, without need of test weights, after the new coordinates are entered. The correction is within 0.01% anywhere on the earth's surface.

Key Benefits:

  • Very low noise, very fast settling, high stability
  • Customize your own base and platter to your unique design
  • High volume production gives competitive prices
  • Delivery from stock
The Auto-Cal Advantage:
Auto Cal is a shunt-calibration system that, when used with suitable Auto Cal load cells can eliminate test weights after the initial calibration. Shunt calibration is a method of using a resistance in parallel with one arm of the load cell bridge to simulate a known load. Once the scale is calibrated, the resistance is switched in and the reading recorded, for use in subsequent accuracy checks and recalibration. When load cells are manufactured to tight tolerances they can be interchanged without need for recalibration, contributing further to the Auto Cal system. Auto-Cal is optional on the 1X3-1945.

For more information about the New USB Weight Transmitter from Scale-Tron click here.

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