Comments- The Base of PLC

This article, presents certain the problems from based on the PLC. I recognize little of this difficulty as problems, I classify as dependent of the route, way, opportunity to know (study).

It would like accounts, of those that they witnessed these difficulties.

And also where do I find the answers (posts) related the questions stops item: "1-1-2) Problems from specialists' point of view " Mainly "(1) Comprehensibility of
ladder diagram and program " links post about concept and sytle programming.
Here article

The article is nonsense !

It seems that the authors of the article hasnt grasped what a PLC is, or what the programming capabilities of current PLCs are.
The article assumes that only ladder diagrams are available to todays PLC programmers. Not so, most modern PLCs have a graphical state-based programming language in addition to ladder.
And there are other languages available to suit other kinds of applications.
So the need for yet another programming language isnt explained very well in the article.

There "article" describes how IF-THEN commands in the "PSC" controller is supposedly easier than ladder.
To my opinion, to use basic or pascal like command syntax can be an advantage, but also a disadvantage in terms of program readability.
The authors seems to forget that the ladder programming that they criticise is actually quite graphical, whereas the proposed IF-THEN style is textbased.

There are many other errors in the article that indicate that the authors havent got a handle on what they are talking.

This looks like advertisong. The controller in question is probably suited for niche applications, but is going to have a tough time displacing PLCs and PC based control for broad based industrial control.

LOL

Here's a few excerts from there web site



PSC Developers Group is a voluntary group of mechanical and instrumentation engineers sympathizing with the idea of PSC and trying for proving its practicability by a reference application. No control engineer is in the group.

We feel deeply grateful for users showing interest and having adopted PSC in spite of two failures. We believe we have proven by ourselves that a sequence control can be planned and materialized without specialists of control engineering.

AS we think we have finished our first step to apply PSC to a practical control to prove it really works, we should proceed to the next step, industrialization and marketing. Many points in the second step need cooperation of specialists on control in refinement of software of PSC by reinforcing its function if necessary, standardization of hardware by optimizing specification and refinement of the structure of the system. These points must be solved by cooperation of specialists as they are beyond ability of mechanical and instrumentation engineers.

Ladder programming IS a form of If-Then statements. They just prefer not to call it that.

Very misleading.

Some modern day PLCs have IF, IFNOT, THEN statements available for a start.

Even in ladder programs can be broken into subroutines etc so that the whole program is not scanned all the time.

Extensive interrupt routines are available.

One could continue on pointing out where they have not grasped the concept of the modern day PLC but I guess it is really pointless.

(4) Scanning of the whole program
Execution of the control is based on scanning the whole program. All of the past, present and future of the sequence are described irrespectively in a program. Therefore, PLC does not allow, by its principle, to scan exclusively the part currently necessary instead of scanning the whole. This suggests a danger of wrong operation due to error of program and it is difficult to find the error beforehand.

Click to expand...

BALONEY! I can write a PLC program that "exclusively scans" parts of the program. And I know 90% of our members don't need me to explain how.

This article is all about paradigms. It's like these guys have been driving Fords all their lives and can't figure out how to steer a Chevy... Ladder logic is just another "flavor" of programming. If you get the fundamentals of how computers "think," you should be comfortable with most anything.

AK