For Ron Beaufort and others... RSS File

Ron, (and others interested)

Here's a sample of one of the programs that we use at a customer site.

This is just a small program, but an example of what I will have to understand and support, once I get up to speed.

Take a look and see if this is something that you think I would have a chance at....


Jim

Greetings Jim,

there is nothing in this program that should give you any serious trouble ... the various instructions all seem to be well commented ... and that’s a good thing ... on the down side (very minor), there’s not much here as far as documentation (specifically rung comments) to describe how the program actually operates the machinery (sequence of operation, etc.) ... but then there are a LOT of programs out there with much less documentation than what you have to work with ... I’d be willing to bet that anyone who is fairly well acquainted with the machine’s operation would have little or no problem working with this program ...

if I HAD to offer at least one suggestion, I’d say experiment a little bit with the TOF (Timer Off Delay) instruction on your trainer ... these work sort of “backwards” to most people’s way of thinking ... still even here there’s nothing to cause you any concern once you understand what’s going on ...

and incidentally, most beginners out there would love to be in your shoes right now ... it’s nice to have a boss that buys you neat toys to play with ... and then pays you to play with them ... be thankful ...

good luck ... and keep us posted on your progress ...

Thanks for the reply, Ron. Yes, I am lucky in that I am the only person running my location's office (Fort Wayne, Indiana), so I can get pretty much what I want as long as I justify it.

I also get nearly all the training that I ask for. I've been to two Rockwell classes that were each a week long, and I'll soon be going to another Rockwell class that covers Panel View operation and programming.

I'm really hoping that I can catch on to this quick, as I'll soon be 50 yrs old, and I want to be able to be productive for a least a FEW years !!!

Thanks again...

Jim

I would recommend that you have a "plain english" overview written for each application.

Something like:
This system monitors and controls the in feed of parts from two bins to an ABC machine, and sounds and alarm if one of the bins runs out of parts.

If it's a short statement like above, I just inclued it in the first ladder documentation. It helps latter, when you trying to figure out exactly what this system does. If it's a longer description, I keep it in the same directory as the program file, for future reference.


Just a thought.


KEn

My 2 Cents are to break the program up into specific files, eg PV Commands and Machine Logic.
As stated in the previous posts, the more documentation the better. The more organized, the better the presentation.
I always seperate the Files, even if there is only 2 rungs in each file. It makes it clear to the people looking for a specific problem of where to look in the code.
There is NOTHING WORSE than 1200 rungs in one File. BREAK THEM UP PEOPLE!!!

Thanks everyone, for your replies.

Kcarlen: Could you possibly give me an example of how YOU would break up this program?

This was written by a controls engineer that was VERY knowledgable(sp?) in what he did, but he had a hard time simplifying things so that I could catch on to what he was doing (or else he didn't want me to know !!! )


Thanks...

Jim

kcarlen said:

My 2 Cents are to break the program up into specific files, eg PV Commands and Machine Logic.
As stated in the previous posts, the more documentation the better. The more organized, the better the presentation.
I always seperate the Files, even if there is only 2 rungs in each file. It makes it clear to the people looking for a specific problem of where to look in the code.
There is NOTHING WORSE than 1200 rungs in one File. BREAK THEM UP PEOPLE!!!

Click to expand...

Totally !

One program with even 500 rungs is a headache if badly documented!

Break up all the specific parts into subroutines and break them down further with instruction comments and rung comments and it all becomes easy............ so to speak

For example, make a new file and copy rungs 17-24 into that file. Rename the file TRX_HMI, and say another for the RX_HMI (Any commands and integer passing from the HMI to the PLC)
LAD 2 will now contain only JSR's and CRITICAL clearing of PV data, Machine logic etc.
Make the FILE 3 your Machine code
Make the FILE 4 your PLC Transfer to HMI
Make the File 5 your HMI Transfer to PLC
etc.....

Try to make your BLOCK I/O a seperate file. For example, in large projects move all of the discrete I/O to a location where it can be interpereted properly. (MOV I:1:0 -> N10:12 LENGTH 10 Words) In the user PLC code, there should not be any DISCRETE talk of OUTPUTS. Only use the Binary outputs at this point throughout your program. Now, use the Binary output that you have set and use that in an "OUTPUT" File to enable the actual OUTPUT. That way, you don't need to search all over the program looking for all of the instances that turn SOL A on. They will all be contained in 1 rung, instead of in some cases many times.

This structure will always work well, but really comes down to PLANNING. Have a seperate file for each known function.
Scan time will not become an issue as long as you are talking normal machine's today. With all things considered, you must always be aware of the scan assignment though, indicated in your first JSR routine file.

Good luck, and have a great time writing good quality code!

kcarlen,

Thanks again for the input. Please understand that I did NOT write this code, but this is one of the more basic programs that I will be expected to support once I get up to speed.

Jim

How far is northern Indiana? I once had to work in Kokomo Indiana on a DELPHI project. Is the corn still 8' tall?

kcarlen,

You're too funny !! Everyone knows the corn is 10' tall !! I am located in Fort Wayne, Indiana, which is just about 60 miles north of Kokomo. I used to service Delphi when I worked field service for another company.

Jim