Encoder Help needed Please

[Levi G]

Hi I have Micrologix 1100 and an incremental encoder, what I would like to do is convert the HSC:acc value to inches using a SCP instruction I am not sure how to go about it.
My encoder has a resolution of 1200p/r and the diameter of the wheel is 5"

 

[bernie_carlton]

Just use 0, 1200 for the 'input' and 0.0, 15.7079632 as the 'scaled'. Send the result to a float.

example:

SCP N7:0 0.0 1200.0 0.0 15.7079632 F8:0

Note - you'll have to MOV the HSC accumulator to an integer. The SCP won't accept the long accumulator.

 

[harryting]

SCP is best used for scaling a process variable that constantly varies which is probably not what you are looking for. Simple math function would probably work better.

I assume you know how to work out the math to convert one pulse to inches. Once you get that, multiple that number by the number of pulses to get you the inches.

 

[Levi G]

So 5" is the diameter of the wheel on the encoder. Do I put in the circumference of the wheel (5x3.14=15.7)where you put the 5? correct me if I'm wrong.

 

[Levi G]

Bernie I misread your answer I guess you had it right

 

[bernie_carlton]

No, you didn't misread it. I realized I messed up and edited it, probably while you were reading it.

But I am concerned in that it wouldn't be able to use a count greater than 32767. Will you reset each revolution?

 

[Levi G]

Could I send the scaled value to an integer? what is the difference between a float and an integer?

 

[bernie_carlton]

If getting just unit inches, no decimal places, is fine then go ahead and do that.

Floats can have decimals. Integers can't.

 

[bernie_carlton]

A faster way would be to divide your count by 76.3943

 

[Levi G]

Thanks for the quick info. I think I will use a float.