Add Multiple Values with ControlLogix Compute

[MNJ96]

I am trying to add 9 DINT values with the CPT instruction in ControlLogix and I keep getting errors. I am just choosing each tag with an add symbol in between each one and sending the result to another DINT tag.

Any idea what I am doing wrong?

 

[plvlce]

Any idea what I am doing wrong?

Certainly not without seeing the actual expression and what errors you are getting.

 

[MarkNightingale]

I've just tried it and it worked.

What error are you getting?

 

[Keystone]

The syntax is correct. PLVIce wrote - what is the actual error.
I could think of three possible one:
1. You spelled a tag wrong, so it does not exist
2. You forgot to create your destination as a tag (done this myself)
3. It is possible if you tag names are too long that nine tags may exceed a text limit for the CPT function.

It could be wrong on all three counts but here is my guess with what was given.
Let us know what the issue was when you figure it out.

 

[MNJ96]

3. It is possible if your tag names are too long that nine tags may exceed a text limit for the CPT function

Any idea what this limitation is? I don't see anything about it in instruction help. Using V17

 

[JeremyM]

Any idea what this limitation is? I don't see anything about it in instruction help. Using V17

2048 characters prior to V34. 4096 characters now.

 

[Operaghost]

I always put spaces in between tags and operators. They are not required, but I find they help visually.

Tag1 + Tag2 + Tag3...etc.

I've done what you are trying to do many times. The errors will tell us where it is going wrong. Otherwise we are just guessing.

OG

 

[shanefaulkner]

Confusing the Dest and Expression fields?

 

[JLand]

Can you please give us a screenshot? Or a description of exactly what the error is?

 

[Matthew Modar]

This probably isn't your particular problem, but it may help someone else in the future: I got syntax errors when cutting and pasting formulas from LibreOffice writer into the CPT formula field. The tags were fine, but the software was replacing the minus operator with a different dash character.

If you are cutting and pasting (and why not), you might check that the plus operator and any space characters are recognized by Logix.

 

[I_Automation]

The syntax is correct. PLVIce wrote - what is the actual error.
I could think of three possible one:
1. You spelled a tag wrong, so it does not exist
2. You forgot to create your destination as a tag (done this myself)
3. It is possible if you tag names are too long that nine tags may exceed a text limit for the CPT function.

My first thought OG beat me to - add spaces. I have had times where adding spaces got rid of an error, when it supposedly doesn't matter.


My second thought is Keystone forgot about #4:
4. One of the tags is actually BOOL, not a DINT.

 

[Jlandwerlen]

You still haven't shown or described what error you are getting.

 

[drbitboy]

You still haven't shown or described what error you are getting.

And not just a screen shot, paste the formula into a post

 

[parky]

My best answer is to just try a few, see if that works, then add the others one at a time till it fails, then you either have a variable that does not exist or a typo or the total length is above the allowed, simple solutions depending on the actual error, if too many chars in tags then either reduce the length of them or do two computes i.e. first with an interim tag as the result & the rest + the interim tag to your required tag.