"Names"

So... just out of curiousity...

Those of you that have been around a (long) while... the "Baker Street Irregulars" comes to mind... know that I'm kinda anal about "naming conventions" (that among many other things... yeah, I'm kinda weird that way, but... so what?).

If I were to decide to become a free-agent, as it were, that is, a generally available Process Developer/Maintainer... for any given process, which of course might use any particular PLC, and any particular version thereof, how would I handle the issue of "names" in an existing program?

Would I, in fact, have to go through the pains of discerning the nature of the particular bits, thus deriving the "names" of those bits?

I know, very well, from my "C-Process" days that "source-code" might, or might not (usually not), be available. As such, if the source-code was not available, then the names were simply un-available.

Or is it possible, for any particular PLC, a guy could walk in, and plug-in, with the appropriate software for the particular PLC, and expect to find the "names" available? Somewhere? Anywhere? Somehow?

I expect that the answer is a resounding "NO!" in the majority of cases.

I'm just curious as to whether there are some situations where the "names" do indeed become apparent simply by "plugging-in".

If so, what are those situations?

I'm sure that there are questions of "Program Versions" for some PLCs, in which case, it appears that you can't even see the on-line code, let alone change it, unless you first down-load the current program.

Is that so? What about the names?

I'm just being being curious.

Terry,

Only on some of the newer model PLCs (and a very few rare older ones) will the address names and comments be available directly from the PLC. For all the rest, you must have a copy of the database that resides only on the PC (or a copy of that program) that was used to create the original PLC program. An alternate is a print-out of the database, from which the "names" can be reentered.

Sanity check

Terry Woods said:

If I were to decide to become a free-agent

I wouldn't if I were you. I think you should consider teaching at a local community college. At least you might get some medical benefits.

Back OT ( On topic ), I have visited a few end customers and OEMs to help them with the motion control. While helping I have noticed that some do not have any comments, label or documentation which I find appalling. I must then dig through the ladder and figure out part the deals with motion control.

It it not fun, but it is like playing Sudoku. As you document each item the rest becomes easier to figure out.

I would be VERY cautious about taking on these projects. This usually is indictive of poor management and engineering practices.

If you do decide to go own your own it I recommend you have a couple of good customer lined up first. I know most of the sawmill OEMs are very busy now and they are usually very good about their documentation.

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Terry,

I have done a couple job where there were no comments. I call these detective work.

Luckily, the jobs I have worked on have had a hardcopy of the electrical schematic. This lets you add comments for the hard I/O right off the bat.

If there isn't a hardcopy of the schematic, then my first step would be to create one. Since all the wires are there somewhere they can be traced to their sensors and actuators.

When it comes to documentation, this is where the RSLogix stuff shines in my opinion. I haven't worked with a lot of other packages besides the Moeller and an old Modicon job but I can't imaging anything being better from a documentation standpoint.

Regarding having comments with the program, here I can only speak from the Moeller background (probably not much help here in the states). Since the PS4 series, Moeller has allowed you to save a copy of the source files on a memory card installed in the processor. This would be like if AB let you store the .RSS file on the EEPROM in the processor. The latest series of Moeller controllers all have either a comopact flash or SD card slot but it is still up to to programmer to put the application there so you can get it. It is not automatic as some companies would view the source as proprietary and not want it available.

Like Peter said, the more bits/ registers you identify, the easier it becomes to decipher more.

... How to make a small fortune in freelance PLC Programming...

... Start with a big fortune and keep working until you whittle it down ...

I am just doing a job for a machine manufacturer who's programmer/electrician/cad-man left suddenly and acrimoniously. He took with him everything of use.

They have sold the machine and it is at the customers factory.


They want me to comment the entire program (there is not one label/comment 3000 + steps) alter the code in the PLC and HMI and supply cadded electrical schematic drawings.

They wanted a price for the work too!

I talked them into an hourly rate and Im glad I did - it's a spaghetti jungle.

But because its an hourly rate, I feel no pressure and the job is fun.

If the customer has a standard for naming conventions then I go by that regardless of what previous people have done in the same processor. If I have to use a bit that is already named I leave that bit named as it is since any maintenance/engineer people at the site would be expecting to see it that way if they are already familiar with it.

If there is not a standard at the site, I try to figure what the previous people did and follow it, but I don't agonize over it - I have a budget to meet and figuring out someone elses standard was probably not part of the quote.

If I can't figure out a convention that was followed previously (maybe someone shotgunned it or too many people have been in it and there are 4 or 5 conventions) and there is no standard at the site I go with my conventions.

Peter said...

"I wouldn't if I were you. I think you should consider teaching at a local community college. At least you might get some medical benefits."

Peter, can I have some further, perhaps more in-depth, clarification on that?

If you feel it appropriate to do so, you can E-Mail me at [email protected]

So I haven't been around a long while, so I'm breaking the rules... but if you're re-commenting programs for already installed machinery free-lance, then use names that relate to what the operators and maintenance folks use.

Being an in house guy, I'm sometimes thrown when the manufacturer calls it a hyper-thinga-majiggy and we call it the turbo whatcha-macallit.

Terry Woods said:

Peter, can I have some further, perhaps more in-depth, clarification on that?

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I don't know what clarification you are looking for but I know you could teach PLCs, and probably more, at a community college.
We "Baker Street Regulars" have been on the forum for a long time. I know that in the 1999-2002 era you provided many excellent graphical examples. You should have enough examples and diagrams stored up on your computer to provide useful examples for a years worth of PLC classes.

Your indirect/indexed addressing beer truck was excellent.

It is these examples and real experiences that normal teachers don't have. After all, what have you been doing on this forum for the last 6 or 7 years?

... How to make a small fortune in freelance PLC Programming...

... Start with a big fortune and keep working until you whittle it down ...

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It is these examples and real experiences that normal teachers don't have. After all, what have you been doing on this forum for the last 6 or 7 years?

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i agree with both!