Proper conversion of loadcell signal


Thread Starter


I have an application for a scale. The scale has 4 load cells 500lb @ 3 mv/v using a constant 10v excitation. I'm using a 0 -20 ma 433
BridgeSensor (from TotalComp) to convert the loadcell signal. The BridgeSensor has calibration parameters to Zero and Span its output signal I don't have any numbers on the physical weight of the scale vessels. Should I accommodate this weight in my calibration of the signal or should I set the 0 with the vessels empty? If I need to
accommodate the weight how do I determine this accurately using the loadcell raw output? In my program ( RsLogix 500) I'm using the Scale with Parameters instruction to achieve calibration based on my ma signal but I feel that the hardware calibration needs to be properly setup
first. Any discussion or further related information would be greatly appreciated.
Thanks in Advance.
Roderick K. Duet

Systems Engineer
I. P.S. Inc.
I have read your contents well. Calibration of Multiloadcell platform is as follows:

1. Measure excitation in the junction box.
2. Measure summed output from the loadcell junction box or digital indicator.
3. Output with dead weight x excitation voltage gives the zero output. Using Cal 0 option, set zero.
4. For span calibration, use some physical dead weight of about 40% of the capacity of scale. Say 500lbs - 1000lbs. Keep the weights in platform and calibrate the signal ouput to the physical dead weight put in.
5. COnduct trials.
6. If you do not have dead weights, use a millivolt source. COnnect this to signal wires +ve and -ve and inject the full scale millivolt. say Excitation x millivolt @ Full scale load. e.g 10V x 3.0mV = 30mV. At 30mV injection, you will set the span as 2000lbs.
7.Conduct trials.

If you have any queries, please contact me.
my email address - [email protected]