Sensotec load cell data acquisition

[EABennett]

I am trying to read a Sensotec load cell - model 41 (50,000 lb). I have the serial cable from the load cell connected to a SCXI-1314, SCXI-1520 Module, SCXI-1000 Chassis, and to a Traditional DAQ Card in the PC. There are 6 wires in the serial cable. According to the wiring code provided by Sensotec, two are (+)Excitation, two are (-)Excitation, one is (+)Output, and one is (-)Output. Right now on the SCXI-1314, I have two wires connected to the P+, two connected to the P-, one in the S+, and one in the S-. However, I am not able to get a reading from the load cell. I have followed the procedures in the tutorial "Getting Started with Lebow Load Cell Sensors and the NI SCXI-1520." Does anyone have any other suggestions?

[Sean_C.]

Hello,

Thank you for contacting National Instruments.

How are you trying to take a reading? Are you using Measurement and Automation Explorer? If so, make sure you use a strain task and provide the load cell with an appropriate excitation voltage. You can then test the task by pressing the green "test" arrow at the top of your task window. If you are still not reading anything, try using an external excitation voltage and measure the output with a DMM to verify that the sensor is functioning correctly.

Also, make sure that P(+ and -) is going to the Excitation (+ and -) wires and S(+ and -) is connected to your Output wires.

Please let me know if this does not help.

Sean C.
Applications Engineer
National Instruments

[sfjd]

Dear Sir,

We are using SCXI-1314 modules for strain and SCXI-1315 for LVDT. I have connected one load cell to the SCXI module(we have three such modules). However it is not detecting any signals from the load cell. When I create a strain task with max. 1 and min -1m input, and when pressing test it is showing some absurd waveform with some negative values(This is when i added no weight). I tried to calibrate it using the calibration option in the "device" tab, but it retruned with Error 200380 occurred at strain gauge calibration. Would you please help? I have load cell with gauge factor 2 and Gauge resistance 120. Strain Configuration is Full bridge I. All oher option I left it as default values.

Regards,
Rajeevan

[Erik_J]

Hi Rajeevan,

For proper operation and calibration, you need a bridge completion resistor that precisely matches your nominal gauge resistance.

Please see this KnowledgeBase for more information, it is a very useful KnowledgeBase!

Best Regards,
Erik

Message Edited by Erik J on 11-27-2006 05:25 PM

[sfjd]

Hi

I have connected the load cell using the 1314 terminal block using a full bridge connection. The load cell is of make HBM 200 kips. (Nominal Sensitivity 2 mV/V). The gauge factor is 2 and gauge resistance is 120 ohms. When I created a new task in the measurement explorer, using the new task option for a new volatage task, I am getting some drifting and fluctuating signal as out put (after clicking the test button). I placed some known weights (say 10 kg(f)), still the signal oout put shows no variation. Can you please help. We are struck with our work with this problem. The entire DAQ purchased has become idle now.

Thanks

[garretth]

Hi Sfjd,

It sounds like you are probably using the SCXI-1520. Instead of creating a voltage task you should create a strain gauge task. You can do this from the same menu in Measurement and Automation Explorer. Also, make sure that you have made the proper connections based off of your bridge configuration. A good reference for this is the following document:

http://www.ni.com/pdf/manuals/322583b.pdf (Chapter 2 >> Connecting Bridge Sensor Signals)

Cheers,

[sfjd]

Hi,

I am using 1520 with SCXI 1314 terminal block on a PXI 1052 chasis. I have created a custom voltage task using MAX. I have a 200 kgs load cell. I clicked "test". These are inputs I made:

1. In the setting tab

Max: 200

Min: 0

Full bridge connection.

When I click "Test" without any load applied on the load cell I am getting a DC signal with a value of 200 shown in the graph. When I kept 10 kgs on the load cell no change. Also I did not see any calibration option in the device tab. Is it necessary to calibrate it?

[sfjd]

Hi

Please see the  attachment. I have included the screen shots..

[Jarrod_B.]

This is a duplicate thread.  From now on, let's keep all posts to the following thread:

strain measurements using SCXi 1314

Thanks!