SCC-SG24 & SCC68 (Torque transducer)

HW: PCI6229, SCC68, SCC-SG24, TRT-25 (Transducer techniques, torque transducer) using Virtual TEDS from ni.com
SW: LV 8.2.1, DAQmx 8.3
Hi guys, with the 'rig' above i'm trying to extract the torque of a motor.
Based on what i know, the SCC-SG24 will detect the small change of
voltage in the bridge of the transducer, amplify it can send it to my
DAQ through the SCC68 connector block. The TEDS data will be used to
properly scale my data so that i'll get an accurate Torque vs Sample
graph. I have attached the screenshot from MAX and it shows the
Amplitude vs Sample of my transducer. As you can see the values are
very small, in the mV range. I've tried changing the max/min input
limit to 200m/-200m but it doesn't allow me to do that. And how do i
convert this voltage measurement to torque?
Attachments:
SCC-SG24.JPG ‏125 KB

Hi Atma,
Doing and average of the signal coming from the torque transducer will help better understand what is happening because the torque transducer can be very sensitive and that is why your readings oscillates between -0.35 and -0.39. In the manual page 23 says that (in the picture) those are the offset nulling resistor for AIX.
If no strain is apply to the torque transducer then yes change the resistor until your signal is in average in 0. For the other three times it can be noise, it can be poor connections it will also depends on your torque transducer specs, this is a useful link for basics in torque measurements http://zone.ni.com/devzone/cda/ph/p/id/255, Another very good resource for strain measurements in general is http://zone.ni.com/devzone/cda/tut/p/id/3642 What are the values the other three times when it does not match the wrench? How those the images look when you apply strain? Let’s say you apply a know strain how does the measurement looks like?
JaimeF
Message Edited by Jaime F on 08-29-2007 03:54 PM
Jaime Hoffiz
National Instruments
Product Expert
Digital Multimeters and LCR Meters

Similar Messages

Bridge Offset Nulling Doesn't Seem to Work With SCC-SG24

Does anyone know if the DAQmx "Perform Bridge Offset Nulling Calibration" vi works with the SCC-SG24 modules? We have used our NI-9237 module in the past to acquire dual-channel load cell (thrust & torque) measurements, and calling that vi does a fine job of zeroing out the values before applying the load. However, it doesn't seem to work when we try to take the same measurements using an SCC-SG24 module.
We are able to zero the values manually, by using the nulling resistors and potentiometers in the SCC-SG24. But, whether the nulling resistors are installed or not, we are not able to zero the values using the "Perform Bridge Offset Nulling Calibration" vi. Running that vi does induce a significant offset in the values, but it is not the correct offset needed to bring the values to zero. For example, with no load applied, a torque reading before running the vi may be +1090 in-lbs, and be "zeroed" to -465 in-lbs after running the vi. Running the vi multiple times (to check repeatability) always brings us back to approximately -465 in-lbs.
An additional issue (not sure if it's related or not) is that if we try to run this vi to offset just one of the channels in the task (such as just thrust, but not torque) it will still induce a small offset in the other channel, which doesn't seem right.
I guess I'm not clear on whether the subject vi is performing an operation on the hardware, the software, or both, so I'm not sure whether the SCC-SG24 modules may not be compatible with this vi?
Thanks for any help you can provide.

Hello Dhruser1,
I think that the DAQmx Perform Bridge Offset Nulling Calibration should work for the SCC-SG24 module. Take a look at this article: Removing Large Initial Offset for Load Cell or Strain Measurements with SCXI-1520 or PXI-4220 in particular it mentions that using this VI in addition to the auto zero can introduce an offset. If you're doing both these is likely the cause.
Also, when you specify specific channels using the channels input are you also setting the "skip unsupported channels to false? If not this may be why it affects other channels.
I hope this helps, and if not please feel free to post back with an update after trying these things.
Cheers,
Brooks

Can I measure 2 differential channels on a single SCC-SG24?

I am trying to use a single SCC-SG24 module to excite and measure the
output of 2 pressure transducers. The module is installed in the
ACh2 position of an SC-2345 carrier. When I configure the module
through 'custom voltage with excitation' in MAX, I can set the terminal
configuration of ai2 to differential. However, the other channel of the
module, ai10, can only be set to RSE or NRSE; the other options are
greyed out. I want both channels to be set to differential. Can I
configure the SCC-SG24 to measure 2 differential channels on a single
SCC-SG24? Thanks.

Hi,
I did a little looking into the DataSheet
for SCC Modules, and I found the following schematic.
As you can see there 2 instrumentation amplifiers that make it to where your measurements
are really differential, and then mapped to the NRSE lines in the
SC-2345. If you were to set up the DAQ board for differential it would
simply read the difference between one pressure transducer and the next.
Long story short, you set up the DAQ board for NRSE for all of the channels,
the SCC-SG24 makes it to where you are really taking a differential
measurement. Everything works quite simply in the end.
Regards,
Message Edited by Otis on 10-11-2005 12:56 PM
Otis
Training and Certification
Product Support Engineer
National Instruments
Attachments:
728815-SCC-SG24_Channels.GIF ‏10 KB

SCC-2345 won't recognize the (2) SCC-SG24s I installed

SCC-2345 won't recognize the (2) SCC-SG24s I installed.
They don't show up as a MAX selection. They are installed
in J3 and J4. I've tried moving them to different slots with
but they still don't show up.
We have a 6052E card connected to the SCC-2345. We are
using Labview 7.0 Developer Suit. Operating system is Windows
2000.
The (2) SCC-SG04s we have installed do show up as a
selection and work well.
Can anyone point me toward a resolution to this problem?

Alan,
Thanks for your reponse, it was dead on.
After updating, the scc-sg24s now appear as a drop down selection but now
I have another problem. My PCI-6052 DAQ board now does not appear as
a selection to "add". Immediately after updating NI-DAQ I fired up MAX and
even though the scc-sg24 appeared as a selection, this selection, the
scc-2435, our pci-6052, and all other modules fitted to the pci-6052/scc-2435
appear with a red "X" next to them.
I renamed the existing <Data> directory and allowed MAX to recreate it but the
PCI-6052 appears ONLY as a legacy selection and can not be added/selected to
DAQmx.
I can add the scc-2345 DIRECTLY to DAQmx and also select all the modules
that we have loaded into it, but after I select <OK> I get an error message that I
haven't selected a digital interface
I'm assuming this is because I can't add the 2345(I have to add it directly to
DAQmx) to the 6052 because the 6052 doesn't show as an available option to be
added to DAQmx.
Do you know if there is other software or drivers I need to update?
Again, thanks for your help.
Art Cravener
Dana Corporation
Message Edited by anengineer on 10-12-2005 03:33 AM

Speed measure with DAQ and torque transducer

Can anyone tell me how to convert the voltage i get from torque transducer, which can measure torque and velocity eather. I made a program with labview, but it gives me some voltage. I'd like program converts me that voltage to a velocity.
Thanks for answers.

First of all, we need to deeply understand the signals we receive from the sensor.In my opinion, the information from the datasheet is not the most comprehensive
Sensor requires 12V DC, 160mA excitation.
Torque: 0V-10V, -10V-0V depending on direction - should be connected to AI
Speed 60 pulses/rev - should be connected to counter 0
Angle 360 pulses/rev (two signals- angular encoder) - should be connected to counter 1
What I would recommend is you started with LV examples for:
Hardware Input and Output -> DAQmx
Torque - Analog measurements and then scale the signal to result in strains
Speed - Counter Measurements -> Digital Frequency
Angle - Counter Measurements -> Position
Please find the proper example, scale them properly, make each work individually and in the end, integrate the three examples into one single application,
Mircea

Scc-sg24

Hi to everyone,
I'm using a SCC-68 connector with a scc-sg24 module to acquire a lod cell with this fetures:
-model FN3060
-Supply Voltage 10 Vdc
-F.S.Output 2mV/V
The problem is that the voltage value acquired in MAX is the same that I measure with multimeter as input of scc-sg24 module.
In the attached file you can see an example: the amplitude is about
1mV, but that I expect is 100mV if the gain og the module is 100.
Any suggestion about this problem ?
Thanks.
Bye
Attachments:
scc-sg244.JPG ‏134 KB

Sorry, I think is not the correct section of the forum.

Read/acquire signal from remaining empty channels of NI9205 by modifying the vi of ATI Force/Torque Transducer which uses the first 6 channelsof DAQ card.

Hello,
I am using force/torque transducer by ATI Automation. It provides me with its own vi to measure and write the data of the 6 signals (3 axes Forces, 3 axes torques)
Following is my Ni system: -
cDAQ 9172 chassis: Slot 5 - NI 9401, Slot 6 - NI 9205, Slot 8 - NI 9237. (Excitation voltage to the sensor/transducer (0-5V) using 9237).
I connect the 6 signals from the transducer cable to channels ai0,1,2,3,4,5 in NI 9205(differential). The vi uses a calibration 6*6 matrix to finally display the calibrated voltage data.
Now, I wish to use the remaining availabe channels that empty in 9205, namely ai17, ai18, ai19 for other signal measurements.
ai17 channel is connected to Hall sensor that gives out a square waveform corresponding to the rotor rpm. ai18, ai19 is connected to rotor-motor power supply's voltage and current signal respectively.
But I am not able to access these 17, 18,19 channels from ATI company's vi. The vi loads the complete DAQ card (9205), uses only first 6 channels, hence the array data wire consists of only 6 channels. I can split these into 6 individual signals only.
If I use a separate DAQ task to read channels ai17,18,19, then I get the error that this channels are reserved for some other task. Please tell me how can I access all the remaining channels apart from the first 6.
I am attaching the vi here.
Steps to run the "MEASUREMENT main.vi" : -
Load calibration file:- FT8840.cal;
Load DAQ card: NI 9205
Load ctr0 of NI 9401 (I am using this counter for rpm measurement purpose, this is my addition to the actual vi)
Attachments:
DAQ - Copy.zip ‏574 KB

There's nothing I can do to help. I don't have your hardware to be able to modify your code and to set it up to make sure it runs properly. Most people on the forum probably don't either. This is where you'll have to put your programming and LabVIEW skills to work to solve your problem and make it run the way you want to. If you run into a specific problem and get stuck, then please post back.

Use of different sensors with scc-sg24

Hi,
in my application I've to use two type of sensors with following characteristics:
-a pressure sensor : 10V Ex V , input nominal 950 Ohm output nominal 300 Ohm
(what does it mean? I know that should be a 350ohm full bridge...)
-a load cel: 10V Ex V, 700Ohm full bridge
It is the SG24 able to read this kind of sensors?
Can I use a single SG24 module to read the two sensor using the two
channels at same time?
Thank you,
Pets
Solved!
Go to Solution.

Hi Pets,
by looking at the scc-sg 24 specifications at this link http://www.ni.com/pdf/manuals/371073b.pdf you
you can see that your module has a 10 V excitation which is the same amount required by your sensor.
The module will work with either the 350 Ohm resistance and 700 Ohm, but since it's been designed for a 350 Ohm bridge, this will be more sensitive.
I hope this informations will help you.
Regards
Andrea N.
Systems Engineer ATE & RF - Mediterranean Region
National Instruments Italy

For SCC-FT01 what is the maximum current for a 5 V excitation?

Simple question, Will my SCC-FT01 be able to handle a total current of 86 ma? I have a SCC-2345 and 6 SCC-SG24 I am using the FT01 to limit the excitation to 5 VDC for my 6 load cells.

Have you considered using the +5V reference to limit the voltage to
your load cells? You would have to measure the actual reference
voltage as it will not be exactly 5V and take the difference into
account when you measure the value from the load cell.
Regards,
Micaela N
National Instruments

Why do I have multiple SG24 modules which have lost their ability to supply an excitation voltage?

I have a number of systems using the SC-2345 Carrier and measuring load
cells (full bridge) using the SG24 module. I have had these fail
to supply a voltage after operation for a short (1-3 months, not
continuous use) period, replacing the module seems to fix the
problem. This problem has been recurring, is there an issue with
these modules. I am using these with various daq boards including
PCI-16XE and similar boards (dependent on calibration cycles).
Thanks for any insight or experiences others have had.

Hey icebar,
Thanks for contacting National Instruments. We are not aware of any quality issues with the SCC-SG24. The input range on these devices is -100mV to 100mV, with an overvoltage protection of 28VDC. Problems like yours are usually associated with large spikes that can damage the module, caused by ground loops and so on. More information about your setup would be helpful.
Let us know if you have further questions.
Regards,
Kenn North
Senior Product Manager - Search, Product Data
http://ni.com/search

Use DasyLab to measure torque, rotary position, and RPM

I'm new to DasyLab and am developing an application to measure torque, rotary position, and RPM. I'll be using an Interface T8 pedestal torque transducer with a built-in rotary encoder capable of measuring angular position, speed, and direction. The encoder will be outputting 5V TTL at one pulse per degree. I'm using an MCC 1608GX USB DAQ device capable of reading analog and digital signals. I'm looking for insight on reading the TTL output from the encoder and converting it to angle and speed. Any help would be appreciated.

OK,
If you want to go directly to the 1608 you need to take the counter input and use it as a frequency input. This will give you the Frequency of the encoder that you can convert to RPM but I don't think you will be able to detect the direction.
To my experience the signal is not very stable due to the software pull but good enough if precision is not a question.
Another oprion is to buy an additional small frequency to analog converter that will take a dirrential output. This units can usually be programmed for +/- Frequnecy to +/- rpm.
There are models out there that are designed fo quadrature encoders. The link below is a good example.
www.laurels.com/downloadfiles/LTA-manual-pulse-in.pdf
Tom Rizzo
InSyS Corp.
www.insyscorp.com
Your DASYLab integrator

How to do Torque mode(position-velocity disabled)using 7344 & torque xdcr signal to 7344 ANI chan ?

Seeking advice on a preferred method to do a torque control application using a PXI-7344, a brushless DC servo motor, digital servo drive/amplifier, a torque transducer as the feedback device connected to one of the 7344's analog input channels.
I have several torque testing applications and would appreciate comments from anyone who has done torque control using NI Motion.

There are really two ways that this can be accomplished using the 7344. It can be done manually by reading the value of the ADC and then outputting a corresponding value on the DAC. This is all done in software and is not as fast as the onboard PID loop. This method could also be implimented with a DAQ card.
The second method would be to set the Primary Feedback for that axis to the correct ADC Channel. Since the ADC is 12 bit, this maps the axis to -2048 to 2047 in counts. Then you could tell the axis to move to a certain target position in counts and it would actually be a torque target value, not position since counts is now in torque. I have not done this but theoretically it should work, however tuning the system may be problematic depending on it's linearity
Hope this was helpful.
Regards,
JR A.
Applications Engineer
National Instruments

How to accomplish Torque and velocity control of an axis using NI motion controller

Used torque transducer as a primary feedback. I am able to control the torque. Used Encoder feedback as secondary feedback to control velocity. But when I run the axis at 5 rpm, I observe velocity variations of more than 200 %. What is the nessasary change Should I make to control both Torque, velocity accurately?

Hello,
Here are a couple of suggestions that might help:
- Tune the PID parameters so that step response will be overdamped
- Increase the PID loop update period
- Reduce the noise on the analog signal coming in. 7350 series controllers are going to be better for this because they have a 16-bit ADC resolution versus 12-bit on the 7340 series.
Hope this helps! Let me know if you have any questions regarding this.
Best regards,
Yusuf Cavdarli
Applications Engineer
National Instruments

SCC strain gauge vi

Hi
i am using a MSLC G100 load cell to measure downward force. This is connected to a SCC-SG24 module inside a SCC-68 carrier connected to a PCI-6221 DAQ card. I'm using Labview 7.1.1
Does anyone which VI will simply let me read the voltage off it?
i'll be glad of any help
thankyou for your time.
Duncan

Hi,
an easy way to read the voltage is with the DAQ-Assistant. After you select it, just choose at wich input of your SCC-SG24 you are going to read the voltage. This should work fine.
Best regards,
Joaquin

TEDS vi

Hi guys, i have a SCC68 with a SCC-SG24 module together with a 6229 DAQ card and i want to perform torque measurements using transducers from Transducer Techniques.
Now, the first thing of course is to read up on TEDS and i realise my LV 7.1 do not have VIs as decribed in Figure 10a. The Top Level VI Palette of the TEDS Library for LabVIEW in http://zone.ni.com/devzone/cda/tut/p/id/4470 Thus, i was unable to run an view examples without these VIs.
What are the software and version i need to have these TEDS VIs?

Hi Atma,
Glad to hear you were able to get the library set up. In regards to your first question, the reason people typically want to write data to the EEPROM of their sensor is to update information about when the sensor was last calibrated. This way the calibration information is always available to whomever uses the sensor.
In regards to your second question, yes, you can use your TEDS enabled sensor as a normal task. TEDS enabled sensors essentially save you the trouble of having to setup the sensor specifications before you use it and help protect you against using the wrong specifications for your sensor.
If you would like to read more information about TEDS, I would recommend taking a look here.
I hope this information helps,
Paul C.

SCC-SG24 & SCC68 (Torque transducer​)

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SCC-SG24 & SCC68 (Torque transducer)