When do carriage returns matter?

[steveneads]

I've just been debugging a PLC that wasn't working as I expected. I had the lines:

 

brEndTime = Sys.Time + 0.5;

while (Sys.Time < brEndTime) {brState = 631;} //wait for 0.5 sec

 

This code did not appear to wait in the while loop at all.

 

Adding carriage returns as below fixed the problem:

 

brEndTime = Sys.Time + 0.5;

while (Sys.Time < brEndTime)

{

brState = 631;

}

 

Is this to be expected?

 

Thanks

Steve

[steve.milici]

Technically this should work. If the IDE is somehow mis-parsing the script you might see it in the results of a list PLC in the terminal window.

[steve.milici]

As to the carriage return question – you cannot have a carriage return inside syntactically atomic statements, as in the following:

1. A condition within parenthesis, (Sys.Time < brEndTime) and its statement (if, while ...)

2. An assignment statement, brState = 631

3. An identifier or keyword, brState or Sys.Time - not even spaces allowed here.

 

The curly braces are each syntactically atomic so they can be on separate lines or not. Your case above may be confusing the parser in some way.

[steveneads]

Hi Steve

 

I tried your suggestion, but as far as I could see, the listing looks correct. However, the two versions of code don't work in the same way. Seems a little concerning to me!

 

Steve

[steve.milici]

I tried several arrangements of code (and yours exactly) and could not get your results. What is your IDE and firmware versions? What is the hardware platform?

[finchyt02]

System Info when we encountered the issue

 

CPU:465

f.w. version: 2.1.1.3

IDE version: 2.1.0.107 (by right clicking on the "Power PMAC Suite Application.exe)

 

Tom Finch

[finchyt02]

Hi Steve,

 

I ran the "list SubProg" command on my system above:

 

Here is the broken code:

 

L2=Sys.Time+0.5

while(Sys.Time

 

Here is the working code:

 

L2=Sys.Time+0.5

while(Sys.Time

{

P9087=631

}

 

The IDE doesn't seem to have missed any of the brackets for the broken code

 

Tom

[steve.milici]

Contact me by email - I would like to give you some procedures to try: smilici@deltatau.com

[steve.milici]

We were not able to reproduce this issue in any form. My best guess to the cause would be the introduction of non displayed control characters via cut and paste.

[finchyt02]

You mean like the control characters you'd see if you did:

 

CTRL+R, CTRL+W.

 

or

 

Edit -> Advanced -> View White Space

[steve.milici]

Also characters above ASCII 127.