Re : I can not measure strain gauge

[Wilfried_71]

Your sensor is working well completely ! I said you this in my first answer of this post : the values read are VERY SMALL. When there's no load, you have a small noise that can maybe be reduce by shielded wires. And when you press the sensor, the values decreases (so it's a compression !) up to 60e-6 ... You can see that your input range is from -1m up to 1m, so it means a maximum value of 0.001 and a minimum value of -0.001. So the changes cannot be higher than this. Now, you've just to calibrate your sensor on a tensile machine and apply the good multiplying factor and you obtain directly the load.

I

[immortal]

Hi Wilfried,

Thank you for your firstly. I changed the property of "DAXmx read" to "Analog 1D DBL 1Chan NSamples" and multiplied with a scalar. I see the changes fairly good now :). I want to ask a question with diff, RSE and NRSE modes. I use NRSE mode and connected the output of sensor to ACHX+ and ACHX- of SCC-SG04. Should I connect the output(-) of sensor to AIsense and output(+) of the sensor to ACHX+, with working NRSE mode?

Kemal

[Mark_E]

Hi Kemal,

The connection configuration with the least amount of noise is differential. Take a look at the SCC-SG Series User Guide and Specifications. It outlines the different bridge configurations, connections, specifications, and even theory of operation. I’ve included some additional KnowledgeBase/DevZone links below that may help if you have additional questions.

SCC Tutorial Series: SCC-SG0x

SCC-SG24 Not Listed as an Accessory to the SC-2345 in MAX Configuration

Filtering Out 60 Hz Noise When Using the SCC-SG04 Full Bridge Strain Gauge Module

Why Am I Getting Noisy Measurements with My SC-2345 Signal Conditioning Modules?

[Wilfried_71]

Yes, you need absolutely a differential connection (small signal = noise issue). For your information, you can set the DAQmx read to the waveform type and multiply directly with a constant (a constant you must create independantly) and it works too !

[immortal]

Hi Nick,

In NRSE mode I connect the load cell to the SCC-SG04 (O(+) -> ACH(X)+, O(-) -> ACH(X)-) and I take the strain data but have some noise. But I haven't worked with Differential mode. Is the differential mode that you said me before working correctly? I connect the load cell to the SCC-SG04 (O(+) -> ACH(X)+, O(-) -> ACH(X+8)+) and select the Input configuration as Differential in the NI6221 test panel and chose the channel name aiX. I see just a DC value which amplitude approximately -10.5. Am I taking a mistake in this configuration?

Best wishes.

Kemal

[Mark_E]

Kemal,

I won’t get into the theory of strain gauge measurements, but suffice it to say that you will connect your strain gauge or load cell as differential, even though you will only have the option in your task to use “NRSE”. You will connect CH(+) -> ACH(X)+ and CH(-) -> ACH(X)-. For all connection purposes, use a differential mindset. If you have a second gauge, you would connect the positive and negative inputs to ACH(X+8)+ and ACH(X+8)-, which will route to the next differential input channel through your DAQ card.

Make sure that you use the correct configuration, such as full bridge I when connecting and you should be fine.

As always, I recommend using the user manuals as a great reference tool. (See my previous post for links.)