Scope of the weight transmitters or strain gauge amplifiers
Depending on the model, the weighing transmitter has several separate signal inputs to which the individual strain gauge sensors can be connected. 4 to 6 inputs are common, so that, for example, 4 load cells can be connected to a scale. The measuring amplifier now generates an electrical pulse, which is then processed and output via an A/D converter (load cell evaluation). A particular advantage of an external measuring amplifier is the fact that the output signal can be adapted directly to the required format. Display modules or PCs with measuring software can be controlled via an RS485 interface. At the same time, the analog output signal can be evaluated by a PLC control system. Some amplifiers convert the signal directly for use in fieldbus systems such as Profibus or ProfiNet.
Summary and Conclusion
Strain gauge measuring amplifiers not only ensure that the measured values are prepared for the control unit, but also enable the use and evaluation of strain gauge sensors in bus systems. They also enable larger distances to be bridged, so that the measured values can be precisely evaluated even at more distant locations.
What does a weight transmitter do?
A strain gauge amplifier converts the signal from a load cell into a reproducible, measurable, digital or analogue signal. Load cells work in the mV/V range. This means that measuring or recording this signal without a corresponding strain gauge amplifier, or simply called a "strain gauge amplifier", is hardly possible. In order to process the signal further with a PLC (programmable logic controller) or a scale display, the strain gauge amplifier converts the signal from the load cell. The analogue output signal of the strain gauge amplifier is 0-20mA, 4-20mA and 0-10V. Strain gauge amplifiers also offer the option of outputting the signal from the load cell digitally.
What types of strain gauge amplifiers are there?
There are DMS measuring amplifiers that can be calibrated and those that cannot. DMS measuring amplifiers can be used as control cabinet installation variants, as a "stand-alone" module or permanently installed in scale displays and PLC measuring cards.
What signal outputs does a strain gauge amplifier have?
DMS amplifiers are available in different versions. With serial interface or analog output with 0-10V or 0-20mA or 4-20mA.
How can I use a DMS amplifier?
DMS amplifiers require a power supply and can be connected directly to the load cells. The load cell is supplied with voltage by the DMS amplifier, which can be supplied with 12 to 24 VDC.
For which applications do I need a strain gauge amplifier?
You always need a strain gauge measuring amplifier when you want to evaluate the measured value of strain gauge load cells. Strain gauge load cells are used in scale construction. Strain gauge load cells can be used to measure tension/compression/torsion forces. A classic table scale usually contains a load cell, an integrated strain gauge measuring amplifier and a scale display. Silo scales consist of several feet that pass the weight change on to a strain gauge measuring amplifier via a weighing module.
Can I connect the strain gauge amplifier directly to the PLC?
DMS measuring amplifiers convert the signal from the load cells into an analog or digital signal that can be read directly by a PLC (4-20mA or 0-10V are the standard here).
How many load cells can I connect to a strain gauge amplifier?
Depending on the type, up to 4 strain gauge load cells can be connected to octogon strain gauge amplifiers. Cable terminal boxes, also known as junction boxes for load cells, are often used. Here, up to 6 load cells can be connected in parallel and passed on to the strain gauge amplifier via a cable.
