CX simulator - problem - CXONE 3.0

[pszczepan 2]

Hi No Error during compiling I am working on some FB Structured text and when I start CX simulator it goes to stop/program. When I try to switch to monitor I got "Communiction Error" = no connection with CX simulator and process CxCPUmain makes 100% of CPU. If I cut off some parts of code I can test this FB - is there some problem with CX simulator? Could you check if you have the same?? FB_structured_test.cxp Thanks Pawel

[pszczepan 2]

OK I got it - it is a problem with WHILE DO statement. If the WHILE condition is not meet CX simulator stop connection. Resolved Edited 7 May 2010 by pszczepan

[CX_Luigi 1]

i guess you tried to use the statement same way you would do in a computer software,continuously checking a logic condition, but the iterative instructions in STL needs to handle directly the condition variables within their cycles, otherwise they will hang PLC and/or simulator. It took me a great deal of attempts and the final help from the forum to get the hang of it, although Omron could have been a little clearer in their documentation.

[dweste 0]

I didn't exactly get what you meant, but now I do After some fooling around with a problematic FOR loop. This works in a PLC, but not in the simulator: Month := WORD_BCD_TO_UINT(AND(RTClock_YYMM,16#00FF)); FOR CalcMonth :=1 TO (Month - 1) BY 1 DO TotalMonths := TotalMonths + 1; END_FOR; This works in a PLC and sometimes in the simulator: Month := WORD_BCD_TO_UINT(AND(RTClock_YYMM,16#00FF)); MonthMinus1 := Month - 1; FOR CalcMonth :=1 TO MonthMinus1 BY 1 DO TotalMonths := TotalMonths + 1; END_FOR; This works in both the PLC and the simulator: Month := WORD_BCD_TO_UINT(AND(RTClock_YYMM,16#00FF)); FOR CalcMonth :=1 TO 12 BY 1 DO IF CalcMonth >= Month THEN EXIT; END_IF; TotalMonths := TotalMonths + 1; END_FOR; In my humble opinion, it's bad coding by Omron. If you can't calculate variables in a FOR / WHILE statement, the compiler should error it [edit] Updated with third example. [/edit] Edited 22 Mar 2011 by dweste

[CX_Luigi 1]

It is not bad coding, but a necessity from the relatively limited hardware resources which the FB compiler is gonna allocate. The following topic sums the question quite nicely and cleanly: recursive instructions in ST FB problem

[dweste 0]

Nope. It's not the same problem. In my FOR loop, the CalcMonth is updated every cycle, so that's no problem. The code runs in a PLC, only the simulator errors. This problem is recognized by Omron, and the guys in Japan are going to fix it. Edited 18 Apr 2011 by dweste