Siemens world simple logic question

[kamenges]

Originally posted by L D[AR2,P#0.0]:

Back to the ladder, the stuff on the left of the coil is evaluated first so it is showing correctly.

So your assertion is the OP just happened to catch that first screen shot on the scan that M202.0 went high due to the top branch? Because on the next scan M202.0 would be true heading into the rung and the contact would match the output status.

Keith

 

[L D[AR2P#0.0]]

His network 2 resets M202.0 every scan.

 

[kamenges]

Originally posted by L D[AR2,P#0.0]:

...I would say that the plc has a limited stack trace of the accumulators and the display gets hold of that to display the data on the screen.

I would buy that. The development would need to indicate to the plc what section of code the stack should start filling from but that is a pretty straightforward exercise. Similar to how Rockwell does data trends but much more dynamic.

Keith

P.S.
I was about to delete that last post about the ladder. I saw the error of my ways.

 

[geniusintraining]

Looks like we are going to get another Christmas quiz

 

[drbitboy]

huh. I guess it makes sense: even if the instruction does not execute, its object's data are recorded.

 

[m_turk]

Wow.

So TIA screens show the input and output of the instruction then, the same as the contacts in the OP. What does TIA show for the variable in the variable list?



A-B is different, to be sure.

I learned plc on Siemens, and it was the same on Simatic manager as L D[AR2,P#0.0] said.. So the first time I got a AB to upgrade and went online, the program was working ok, but every other network didn't make any sense.. That was fun

 

[parky]

The first pic is illogical as you would never use it where you enable a bit as true then disable it as false, the second is logical as it will process any logic between the double coil, hence I think the OP has learned a valuable lesson not use duplicate coils as out instructions unless you have some other logic it works on in between the two out coils. The other thing is how the monitoring function works
1. Communication for on-line monitoring done at the beginning or end of scan.
2. By interrupt (could be on time or some other function like request).
3. Communication processor works on it's own in parallel with the main processor but can look at the memory map.