Phidgets Forums

Hello,

I have actually a micro Load cell connected to a Phidget bridge with 4 input.

When I am on my computer, I can see a voltage shown, that I convert to grams.
The question is, I have a voltage between 0.001 and 0.002 (not exactly but around this), how can I change this range, for example from 0 to 1 volts? Is that possible?

Thank you for your help.
Regards.
Quentin.

When you say you're converting to grams, do you mean you're using the Phidget control panel and using a calculator to convert to grams manually?

The best solution is to write your own Phidgets program using our API, and then you could convert to grams automatically in the program, and have it display the number in grams on the screen.

Hello mparadis, and thank you for your fast answer.
Actually, I have a program made with labview, and with calculation I convert the voltage to grams automatically.
Everything works fine, the only question I have is about the RatioVoltage value, for example, now I have, for 0 grams a value of 0.0017 and for 100 grams, I have a value of 0.022 or something like that.
So, the Ratio voltage come directly from the sensor, but what I want to know is, is that possible to change the range of this value, from 0 to 1V for example?

Thank you again.

I'm not sure what you're trying to accomplish if you already have the result in grams.

Regardless, the 1046 outputs a voltage ratio, which is the ratio of the voltage supplied to the load cell to the voltage returned by the load cell.

For example, the 1046 might supply 4.96V to the load cell this moment. If the load cell returns 0.109V, that would be a voltage ratio of 0.022. In the next moment, the voltage provided by the 1046 might fluctuate slightly to 5.01V. If the strain on the load cell remained the same, it would output a voltage of 0.11V, which would still result in a voltage ratio of 0.022. As you can see, voltage ratio serves to remove noise from fluctuating supply voltages.

Thank you for your answer.
Well I understand what you are saying.

Last question about this bridge, is there is anyway to have a diagram of it? To see the path between analog to digital value, etc...

Thank you again

I don't have a block diagram handy, but the data path is pretty straightforward:

- A voltage comes in from the load cell to the + and - pins on one of the 1046's channels
- These pins are read by a 24-bit ADC chip
- The values are transmitted from the ADC to a USB processor chip via serial
- The USB processor converts this data into USB packets
- The USB packets are received by our software libraries running on your computer
- The values are made available in your program via the VoltageRatio change event, or by a getVoltageRatio call

Thank you for your help.