RSLogix5000

In RSLogix5000, has anyone figured out how to get all rungs to "wrap". I have "rung wrapping" as well as "wrap branches" checked, yet throughout the program certain rungs remain "un-wrapped".

Not a major thing, just one of those little annoyances.



That is, of course, if I correctly understand the definition of "wrap"

This happens to us to. I don't think it knows how to wrap when there are branch levels involved. I have an annoyance in that when I open the Controller Tag browser, the Edit tags tab is showing (in front)instead of the Monitor tags.

You dont even want to get me started with the little things in RSLogix 5000 that drive me insane!!! banghead mddr

Has anybody had this problem:

I enter the number -0.580 into a tag with the data type REAL. Press enter, the number comes back with the value -0.57999998 (or something similar). We talk to our AB reps , they tell me its a "windows rounding error"

Oh well... whatcha going to do

Steve Crotty said:

I enter the number -0.580 into a tag with the data type REAL. Press enter, the number comes back with the value -0.57999998 (or something similar).

Click to expand...

I have noticed this also. I have just ignored it, as .000000001 usually doesn't affect me.

screen shots

93lt1, I have noticed you using screen shots from time to time and wanted to complement you on their quality. I have tried several "free" screen capture programs including the one in HTML Help but they always seem to be fuzzy when I look at them later. It may be that I save them in JPEG format to save memory space. Which software do you use and which format are yours saved in? Tips would be appreciated.

Screen Shots.

Most often I use a program called Full Shot '99. Kind of an old program, but it is easier to capture a small area. If I am doing a full screen or active window, I use 'cntrl'+'print scrn' or 'alt'+'print scrn'.
Either way the result is a bitmap (.bmp). I then open in MS Paint and do a 'save as' type .gif. I have never tried to save as a jpeg when doing screen shots.

I have found the thing that really distorts the pic is re-sizing.

When you say "view them later", what program do you use to open them? On my home P.C. (Windows ME) the defualt program for most pictures files is Image Viewer(?) or something like that, but it always "shrink to fit" the image into the screen. It always messes up my screen shots, but there is a button at the top to view actual size.

The best way to tell how they will look when attached to a post, is right click the pic and select 'open with' and select 'Internet Explorer'

My default viewer used to be IE but that changes from time to time and I am not sure why. However, I understand your comments and will take a look at it. I use jpeg format because it is a picture but the gif formatting may work better. I appreciate your taking the time to answer.

I have noticed this also. I have just ignored it, as .000000001 usually doesn't affect me

Click to expand...

You must not use very many equal to instructions. I am very glad that somebody else is having this problem and im not crazy

May I ask you what version of RSLogix you are using? we use V10, and I was wondering if maybe this went away in V11 & V12

Version 10

I really don't have a lot of experience with floating point numbers in CLGX, but I did a small project calculating uptime/downtime/uptime percentage, where I used floating point.

But I agree, If it was a Windows ( ) rounding error, why doesn't it do the same in RSLogix 5/500??



This is some very "good to know" information. Anyone else have any of these little "catches" pin-pointed?
Hearing about them now could save some time in the future!!

I'll be one of the first to admit that RSLogix 5000 hasn't perfected it's user interface. There's a whole RSI forum section dedicated to complaining and suggesting things about Logix 5000.

The RSLogix 5000 handling of floating point numbers is not a Windows error at all, it's a matter of IEEE 754 single-precision data handling.

RSLogix 5000 developers were told to omit the convenience feature in RSLogix 5 and 500 that truncates the display of floating-point numbers to the last nonzero digit. The values themselves are not rounded at all; they retain all the precision that the IEEE 754 Single-Precision Floating Point method can give them. Only the display is simplified.

As an example, enter the value 0.580 into a Floating Point register in RSLogix 500. It displays as "0.58".

Now enter it into a REAL data type tag in RSLogix 5000 version 8.02. It displays "0.57999998".

Why the difference ?

It has to do with the way any digital computer handles floating-point values. The standard method is called IEEE 754 Single Precision Floating Point, and it's used by PLC-5, SLC-500, and ControlLogix to use 32 bits of data to represent a floating point number. One bit for Sign, 8 bits for Exponent, and 23 bits for the Fraction (aka Mantissa).

There have been numerous discussions of this on this Forum and others in the past; do a Google search on "IEEE 754" and you'll find some of them.

The one I like best is here:

http://babbage.cs.qc.edu/courses/cs341/IEEE-754.html

Go type in 0.58 there and it will show you all 32 bits that the PLC will use internally, as well as indicate that the scientific notation is 5.7999998e-1

I also tried entering floating point numbers into RSLogix 5000 version 11.10, and the are displayed with the same truncation that RSLogix 500 uses. I guess sensibility finally triumphed !

I've noticed the same thing in a couple of programs I've done in Logix 5000. Once you add the branches you seem to lose the rung wrapping. No one that I've talked to about this can explain why it happens. Just another AB idiosyncrasy that we ahve to deal with.

Regards
Dave

Ken, I wish I could pop out answers like that!!

Ken Roach said:

RSLogix 5000 developers were told to omit the convenience feature in RSLogix 5 and 500 that truncates the display of floating-point numbers to the last nonzero digit. The values themselves are not rounded at all; they retain all the precision that the IEEE 754 Single-Precision Floating Point method can give them. Only the display is simplified.

Click to expand...

Steve Crotty said:

You must not use very many equal to instructions.

Click to expand...

If it is just the display, not the PLC, what is the deal with Steve's problem with comparison instructions in RSLK? Steve? Ken?

I also tried entering floating point numbers into RSLogix 5000 version 11.10, and the are displayed with the same truncation that RSLogix 500 uses. I guess sensibility finally triumphed !

Click to expand...

Ken, so just to double check that last statement, you are saying that glitch (or whatever you want to call it) is fixed in version 11.10?