SCP operand size error with 1762-OF4 card

I have been reading past thread for this problem, but i can't find a solution to this problem.

I have a MicroLogix 1400 with a 1762-OF4 AO card.
On my PanelView I have put in an input box for operation to enter a value between 0 ~100%, this controls an output from 0~10V on my output card.

So I have used a SCP function to do this. Here are my SCP settings:

Input: N7:0 <---Pass by operator
Input Min:0
Input Max:100
Output Min:0
Output Max:32767
Output:O:4:0

Every time when I try to verify my project, an error pops up saying something like "Operand size does not match", but there is no error when I try to verify the program individually. Only happen when i try to compile whole project.

Can anyone suggest why this is happening?

You are entering the address wrong.

O:4.0

not O:4:0

I recommend you range check your input value before the SCP so that it cannot be greater than 100 or less than 0.


Here is the addressing manual from AB's literature library.


Other manuals for the ML1400 can be found here.

When I tested "O:4:0" the validate immediately caught the addressing error. Not the error noledge is seeing.

To noldege, are you sure the error is with this instruction?

Post your .rss file if you can. Zip it first then post.

Sorry that was my typo, yes you are right, it's O:4.0 that I have typed in.

I have close the program and re-open up the file again.
This time when I am trying to verify the project, I didn't have any problem at all ??? Weird, but yeah problem is gone.

Wonder if that is because I didn't assign an initial value to N7:0, and it overflows or system detect an out of range number for my setting during compile.

Double check your output raw scaling values, I just used the same card with an 1100 and my min/max were configured 6240/31206.

I think I have found the problem, it is something to do with the floating point. This same problem happens again when I was trying to change my input maximum to 10.5
Whenever my values in the setting has got a decimal, then this problem occur. (Include 10.0)
So I just change all my Input to a floating value, and the problem was solved.

Correct me if I am wrong on this

At this link go to the 1762 OF4 link ,then onto page 14
My reading of what is said is at full scale for 15 bits 32767 will equal 21 mA or 10.5 V so 20 mA or 10 V will be a lesser number.
If you go above 32767 then output will step from 21 mA to zero.

The Integer file may have seen the 10.5 value entry as if it were 105 ignoring any decimal points, as Integers are only whole numbers.

http://literature.rockwellautomatio...0014&FamilyId=0104&passedLangVal=EN - English