New to anilog signals. Using a 5-10vdc analog load cell not to exceed 15vdc straight to the input card on a micrologic 1400 processor and not getting the results i desire. At 10vdc each pound = 1. At 5vdc every 2 pounds = 1. At 15vdc each pound = 1.5, but i do not want to push the voltage limit. What would you recommend to be able to take the signal and be able to come within say .2 pounds
Load cell help
- Thread starter sharkyh2o
- Start date
James Mcquade
Member
sharkyh2o,
welcome to the forum.
typically load cell outputs are in millivolts, not a 5-10 volt output. the specs usually say x volts per millivolt when using a load cell amplifier.
post the brand name and model number of the load cell and plc.
if it is as you say a 5-10 volt output, you will need to determine the exact output and do a scale (SCP) function.
regards,
james
welcome to the forum.
typically load cell outputs are in millivolts, not a 5-10 volt output. the specs usually say x volts per millivolt when using a load cell amplifier.
post the brand name and model number of the load cell and plc.
if it is as you say a 5-10 volt output, you will need to determine the exact output and do a scale (SCP) function.
regards,
james
bernie_carlton
Lifetime Supporting Member + Moderator
The input can take up to 10 VDC. The circuitry is 12 bit A/D. This means the 10 volts is divided into 4095 segments. So, using the load cell at 10 volts, you will will have .0002 pound accuracy.
As James notes, most load cells have a very low voltage output and require an intermediate amplifier. Just out of curiosity can you provide a reference to data on this load cell?
As James notes, most load cells have a very low voltage output and require an intermediate amplifier. Just out of curiosity can you provide a reference to data on this load cell?
Last edited:
i was expecting 4095 segments but i am not getting that. it is a 100 pound load cell and at 10vdc i am getting 0 at 0 pounds and 100 at 100 pounds. Sorry i am so vague, not at work now. I will get the specs tomorrow, just cant get this problem outta my head and i found this site. Learning as i go.
bernie_carlton
Lifetime Supporting Member + Moderator
Post your wiring diagram, both from the load cell documentation and how you actually wired it.
George Graziano
Lifetime Supporting Member
Does it go from a number of load cells to a summing board? They can be 10 volts at that point. As others have said a model number of the load cells and quantity.
George
George
James Mcquade
Member
George,
good point, i didn't think of that.
james
good point, i didn't think of that.
james
kamenges
Member
gbeaker, the load cells you are familiar with use foil strain gages. Many of the load cells I use in the web handling industry use semiconductor strain gages. For example the CMC load cells we often use contain semiconductor strain gages that produce 20mV/V at rated load.
Keith
Keith
The loadcell needed an amplifier.I thought i could go straight to the input card with the loadcell signal.Working great at 5vdc and 1.6mv out. One more quick question, the lower the voltage the less chance of interfearance correct? Thank you everyone.
kamenges
Member
For comparison's sake in any given application you can consider environmental noise to be a constant. That being said and all other things being equal, the larger your actual signal level relative to a given piece of "data" the less the "data" will be influenced by the noise in your environment. Basically the larger signal level provides a better Signal:Noise ratio.
I would say use the highest excitation the device is rated for.
Keith
James Mcquade
Member
sharkyh2o,
i have always used shielded cable for the load cell wiring with the drain wire going to the analog card com.
remember to tape the other end of the shield off or risk a feedback loop which induces noise.
regards,
james
i have always used shielded cable for the load cell wiring with the drain wire going to the analog card com.
remember to tape the other end of the shield off or risk a feedback loop which induces noise.
regards,
james
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