HEllo again plc 5/20 cpt what am I missing

[controlconcepts]

have not had much experience with logix 5 and just trying to use the y=MX+b equation to do some scaling in my test rig. The rungs in question are 19,20,and 21 have read many posts on the subject and banging head...... also used same eq in a slc and am not getting the expect results. must be something easy. just looking at it to long. need a fresh set of eyes.

Thanks to all that respond no rush but know how you gurus pick up on this stuff. And thanks to all the others that have helped me last time.......

 

[controlconcepts]

miss fire

here is the code thanks

 

[MarkNightingale]

You have not attached any code

Mark

 

[sthompson]

Can you Post your Program File (RSP) so we can see what is in the N Files. (Zip it first - Forum rule)

Stu....

 

[Ron Beaufort]

a solid hint ...

the figure below should help with the basic format of the formula ...

note also that if you stick with ALL/ONLY integers in your CPT then you're going to have problems with "round off" errors ... you need to have at least one floating point location in there somewhere - possibly more depending on the values that you're working with ...

there isn't enough information in the PDF you posted to allow me to use your specific memory locations ... you should be able to substitute your own locations for the samples that I've used ...

.

 

[controlconcepts]

Sorry it took so long to get back to this post! Thank you all for help. And Ron great to see you back here with your inexhaustible fountain of knowledge. But I tried the formula that you posted and still not working. I am getting ridiculous results. I will post the RSP file and maybe this will make sense

 

[controlconcepts]

here is the RSP

here are all the plcs I am currently working with

 

[controlconcepts]

And I forgot to explain the regester mapping I am asuming
Ron's CPT integer's my integer's in my CPT lad 2 Rung 19
n10:0 = input N14:140
N10:1 = in min N14:141
N10:2 = in max N14:142
N10:3 = scaled min N14:143
N10:4 = scaled max N14:144

 

[jstolaruk]

Use float data types (F) instead of integer (N) for your computations.

 

[controlconcepts]

wow that was fast will try right now

 

[controlconcepts]

Just changed them all to Floats and still way off

 

[jstolaruk]

Break your calculations down into managable pieces that you can check against your hand_written-calculator_checked design notes. I usually find I fat fingered something somewhere.

 

[controlconcepts]

Wow someone else that uses the fat finger term lol. ya found my
(in min in max)
(scl min scl max)
swaped in the eq set Ron posted
but still off but very close pointing to the analog input card needs A CALABRATION

 

[jstolaruk]

Its also known as the ID-ten-T error or fault.

 

[controlconcepts]

As i have the AI"s looped to a slc 5/04 card and the numbers are exact on them.
in the PLC 5 @ 4 ma raw counts = (2070-2085) never steady always bouncing