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Analog input scaling

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Good Day I have trouble with programming Analog inputs and scaling of them on AB control logix with RS logix 5000 its weighing system that has an output 4 to 20 mA and 20mA is calibrated to 50 tons per hour on a conveyor. The problem is on the programming side with the scaling and the recording of it . The requirement is to display Tons per Hour and cumulate it to have total tons . Would appreciate any help on this Andre Kruger

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Scaling is easy. Double-click the analog input module and set the scaling on the module....see pic Displaying rate is a little harder - you have to accumulate the instantaneous value over time - divide the two and you have rate. How you do that will depend on a few factors..... 1. How stable is the instantaneous weight value 2. How quickly does it change 3. How often you want the flow-rate updated 4. How long does it run before reset Simplest is to periodically add the instantaneous weight into a REAL, and divide the REAL by the number of additions. Simplest is most often good enough....

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If you have RS Logix Professional, there is a Totalizer Function Block available for Function Block Diagram (FBD) style programming. I recommend this for the totalizing part of your application. You should be able to use the information from the block to calculate rate, or you can write some ladder to do that.

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