Divide by zero error on PLC 5/40

[akrafter]

I ran across this example in the PLC 5 instruction set help (see attached screenshot). I've run into divide by zero errors before, but I couldn't remember if it was only on SLC's. It seems odd that Rockwell Software would be using an obviously faulty example in their help files...Does the divide by zero error not exist on the PLC 5?

 

[Ken Roach]

My guess is that the screenshot was done just to show the layout of the instruction block, not its function.

The author missed an opportunity to illustrate datatype conversion, and shows an invalid entry.

The more I read this the less happy I am with the text: it includes word and sentence fragments, implied subjects, and omitted articles.

It also doesn't make sense to mention Long Integers in a PLC-5 reference book, as the PLC-5 doesn't support them.

Here on the Forum it's nearly impossible to get users to form complete sentences, so I am starting to despair over the possibility of concise and accurate technical communication, even between people divided by a common language.

 

[OkiePC]

Better?

I left alone the Long Integer reference, thinking it needs a footnote mentioning Softlogix or something?

 

[kamenges]

Now, back to the actual question.

The PLC5 doesn't throw a fault on a divide by zero. It will display a +INF or -INF to indicate the value went to infinity. But it won't fault. That was one of the bigger lessons I learned moving from PLC5 to SLC.

Keith