AB micrologix 1400 counter move

[ateall217]

I'm tring to move the data in F8:30 to st10:60. Anyone have a suggestion?

 

[jstolaruk]

These are two different data types: float and a string. You'll have to utilize the AIC instruction after breaking up the float into some integers. Have you tried a search in this forum, I have to believe its been addressed here before.

 

[ateall217]

I tried moving to and integer file then to a st file but it causes a math overflow error. Im assuming because to value is to large

 

[jstolaruk]

Sounds like you'll need to scale it down and then manipulate the string to show it.

 

[swimmy67]

When moving a Float to a INT you need the change the length of the move instruction to "2". Float is 32 bit and INT is 16 bit.
Example:
F8:0 will fill two ints N7:0 and N7:1

 

[Ken Roach]

Take a step back; these are totally different datatypes. Just 'moving' the values in their bytes doesn't work.

Let's say F8:0 has the value 123.456

MicroLogix controllers use a 32-bit single-precision IEEE 754 floating point datatype. In hexadecimal, that value is 0x42F6E979.

[Nifty online tool at SUNY Queens College]

Converting that to ASCII strings, especially in a MicroLogix, requires more than just moving a few bytes around.

The MicroLogix/SLC-500 operating system doesn't have a REAL-to-String conversion instruction like the ControlLogix/CompactLogix does.

So you'll have to write a routine to extract each digit of the floating-point number by division and truncation, then use the Integer to ASCII (or simpler math adding single digit values to the ASCII value for Zero) to put those values into a String.

It's a little tricky for a novice; I'd probably spend an hour writing and testing such a routine. Maybe somebody has an example handy, or you can find one in the archives.

 

[Mickey]

http://www.plctalk.net/qanda/showthread.php?t=27395&highlight=float+string

 

[swimmy67]

View attachment 1766-rm001_-en-p-CPW.pdf

The CPW command should be able to copy a Float to a String in a ML1400.

 

[Ken Roach]

Ron's been dead for... what, five years ? And he still contributes.

I didn't appreciate him as much as I should have.

 

[ateall217]

Figured it out

I moved the f8 file into a long interger L15: and moved that into the St file ST10:60.

 

[bernie_carlton]

As long as you are satisfied with the result I guess it's ok.

I, just for curiosity, would like to see the sequence of instructions you used, the final contents of the float,long and string and the significance of the value you are moving.

 

[ateall217]

I would if I could get a pic. To post.

 

[Firejo]

I think what Ken is saying (not about the dead guy) is that you might be able to make the move but if not done correctly the data won’t be valid after the move (Ken correct me if I’m wrong).

 

[Ken Roach]

You're exactly right, Firejo.

The instruction will be verified by RSLogix 500, but I don't think Ateall217 will get the result he wants.

Using the MOV instruction will convert between datatypes automatically. For example:

MOV
Source   F8:30  
         12345678.910
Dest     L11:0
         12345678

MOV doesn't work on Strings, except to move ASCII codes into the string data elements.

Maybe ateall217 used the ASCII to Integer (AIC) instruction on the Long Integer value, to convert that to a String. In the MicroLogix 1400, both ordinary N files and long-integer L files can be used as the source for the AIC instruction.

I didn't recomend that at the beginning because he specifically asked about converting a floating point value, not the whole number portion of a floating point value.

 

[ateall217]

I did use the AIC function to convert the long internet to string.yes, I should have been more spisific . I was trying to move a total counter with a value over 39000 to a string file. I tried posting a pic but was unsuccessful.