5v excitation with a SCC SG24

[E.Carroll]

I have a load cell that needs 5v excitation. I'm using DaqCard6036, SC2345 and a SG24 module.How can I provide 5v excitation?

[Brooks W.]

Hi E.Carroll,

The SC-2345 has a 3-tiered screw type terminal block which has +5 V coming out of screw terminal #14. See page 3-7 of the PDF document (link below) for the pin assignments for the SC-2345.

http://www.ni.com/pdf/manuals/371064a.pdf

Have a great day!
Brooks W.
National Instruments

[E.Carroll]

When I use the 5v source from terminal #14 the millivolt input reads negative though the NI-Daq software.The signal at the module terminal is positve. With an external 5v source the input reads positve and is correct.Somewhere through the module,sc board or software something is happening to the signal.Could I possible convert the 10v to 5v on the scc sg24 module?

[Brooks W.]

Hi E.Carroll,

What is the voltage reading coming from terminal #14? If it is 5 V, this will provide the proper excitation for your load cell. Ensure that the leads (from the load cell) coming into the SCC SG24 module are not switched.

If there are still problems, you can use the 10 V excitation from the SCC SG24 module. You will have to get a resistor that matches the internal resistance of your load cell and connect it in series with your load cell. I would not suggest going this route, however it is possible.

Have a great day!
Brooks W.
National Instruments

[cb34]

I have a problem with my scxi 1520 excitation. it seems to me that you have to change twice the excitation values before the scxi 1520 gives you the excitation that you want.

for example, when i turn on my labview and then the chassis, i must enter twice different values before the device recognizes it. for example, if i enter first 5 V, it will not work. i must enter another value different from 5 (say 3) to make it work. otherwise, i will get no excitation.

please help me on this. thanks!

[spcmicro]

 I have the same situation with a load cell that requires a 5 volt excitation voltage. In this thread I didn't see a resolution to the problem. Can the 5 volts from the SC-2345 be used or not?

[Chris_K_]

Hi spcmicro

The SC-2345 has a 3-tierd screw terminal that allows you to access the 5V pin on all E-series DAQ cards.  So depending on which DAQ card you are using with the SC-2345, it will tell you if you can use the SC-2345 to provide the 5V excitation.  You can check this by using a multimeter to measure the voltage between pins 14 and 12 on the screw terminal of the SC-2345.  It should read 5V, and it can be used to provide the needed excitation.  If you have the SCC-SG24, as is mentioned in the previous posts, it provides a 10V excitation from the module itself, so if your load cell needs a maximum of 5V the SCC-SG24 cannot be used, and something else will have to provide the excitation such as this 5V line from the DAQ card.

If you still have questions with regards to excitation, can you let me know which DAQ card you are using, and which SCC modules you are using to measure the load cell? 

Have a great day.

Chris_K_