SCP help with ML1100

gimmephone

Member
Join Date
Mar 2005
Location
Windsor, Ontario
Posts
34
Hi,

This may seem like a very stupid question to you guys but I am a bit stuck with this. I was playing with my ML1100 and trying to scale an input signal to an input voltage between 0-10 to 0-10000.

A screenshot follows.....

First, my question is why is I:0.4 shown as Analog Input0? Does the PLC automatically place a 16-bit result here based on the analog input value (0-1023)?? I ran this code and values of my output seem to change...I will get a better idea tomorrow when I try it out with a variable power supply. Can anyone tell me on the line after where I chose Input inside the SCF instruction as I:0.4, why does a 5 show up and correspondingly a 49 as my output value? Does this me that an input=Common is scaled to 49?

I have worked a lot with Modicon and AB to me seems like hell right now o_Oo_Oo_O!!


Thanks for the help





SCF.jpg
 
Last edited:
Twelve bit (with sign) is 0-1023
Sixteen bit (with sign) is 0-32676

I'm not sure about the ML1100 Input Cards, but if it's like the SLC 500, it's sixteen bit, so your SCP should use 0 low 32767 high.
The analog value is automatically put in the word file of the corresponding input.
 
Also, with your SCP as you have it now,

5/1023 * 10000 = 48.88 rounded to 49.
The 5 value probably means that your reference is floating slightly.
 
Dont you miss 30001 and 40001 right about now!!

I still cant get my head around all this I:0......but i am trying!

Good luck..
 
The analog input I:0.4 is an input on the base module, not on an expansion card. These are a relatively low resolution 0-10 volt input card, 10 bit which is 0-1023.
You can view the input radix in binary or decimal by changing the requested view.
The SCP instruction is just a linear relation. Your input is 5 of a maximum of 1023. (approx 1/200th) This corresponds to 49 of a maximum of 10000 (again approx 1/200th).
Change the N7:0 to F8:0 and make the scaled max = 10
This will give you a floating point value for the voltage applied to the analog input.
Regards Alan Case
 

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